Tony Pearson is a Master Inventor and Senior IT Architect for the IBM Storage product line at the
IBM Executive Briefing Center in Tucson Arizona, and featured contributor
to IBM's developerWorks. In 2016, Tony celebrates his 30th year anniversary with IBM Storage. He is
author of the Inside System Storage series of books. This blog is for the open exchange of ideas relating to storage and storage networking hardware, software and services.
(Short URL for this blog: ibm.co/Pearson )
My books are available on Lulu.com! Order your copies today!
Safe Harbor Statement: The information on IBM products is intended to outline IBM's general product direction and it should not be relied on in making a purchasing decision. The information on the new products is for informational purposes only and may not be incorporated into any contract. The information on IBM products is not a commitment, promise, or legal obligation to deliver any material, code, or functionality. The development, release, and timing of any features or functionality described for IBM products remains at IBM's sole discretion.
Tony Pearson is a an active participant in local, regional, and industry-specific interests, and does not receive any special payments to mention them on this blog.
Tony Pearson receives part of the revenue proceeds from sales of books he has authored listed in the side panel.
Tony Pearson is not a medical doctor, and this blog does not reference any IBM product or service that is intended for use in the diagnosis, treatment, cure, prevention or monitoring of a disease or medical condition, unless otherwise specified on individual posts.
Storage Networking World conference is over, and the buzz from the analysts appears to be focused onXiotech's low-cost RAID brick (LCRB) called Intelligent Storage Element, or ISE.
(Full disclosure: I work for IBM, not Xiotech, in case there weren't enough IBM references on this blog page to remindyou of that. I am writing this piece entirely from publicly available sources of information, and notfrom any internal working relationships between IBM and Xiotech. Xiotech is a member of the IBM BladeCenteralliance and our two companies collaborate together in that regard.)
Fellow blogger Jon Toigo in his DrunkenData blog posted [I’m Humming “ISE ISE Baby” this Week] and then a follow-up post[ISE Launches]. I looked up Xiotech's SPC-1benchmark numbers for the Emprise 5000 with both 73GB and 146GB drives, and at 8,202 IOPS per TB, does not seem to be as fast as IBM SAN VolumeControllers 11,354 IOPS per TB. Xiotech offers an impressive 5 year warranty (by comparison, IBM offers up to 4 years, and EMC I think is stillonly 90 days).Jon also wrote a review in [Enterprise Systems]that goes into more detail about the ISE.
Fellow blogger Robin Harris in his StorageMojo blog posted [SNW update - Xiotech’s ISE and the dilithium solution], feeling that Xiotech should win the "Best Announcement at SNW" prize. He points to the cool video on the[Xiotech website]. In that video, they claim 91,000 IOPS.Given that it took forty(40) 73GB drives (or 4 datapacs) in the previous example to get 8,202 IOPS for 1TB usable, I am guessing the 91,000 IOPS is probably 44 datapacs (440 drives) glommed together, representing 11TB usable.The ISE design appears very similar to the "data modules" used in IBM's XIV Nextra system.
Fellow blogger Mark Twomey from EMC in his StorageZilla blog posted[Xiotech: Industry second]correctly points out that Xiotech's 520-byte block (512 bytes plus extra for added integrity) was not the firstin the industry. Mark explains that EMC CLARiiON had this since the early 1990's, and implies in the title that this must have been the first in the industry, making Xiotech an industry second. Sorry Mark, both EMC and Xiotech were late to the game. IBM had been using 520-byte blocksize on its disk since 1980 with the System/38. This system morphed to the AS/400, and the blocksize was bumped up to 522 bytes in 1990, and is now called the System i, where the blocksize was bumped up yet again to 528 bytes in 2007.
While IBM was clever to do this, it actually means fewer choices for our System i clients, being only able to chooseexternal disk systems that explicitly support these non-standard blocksize values, such as the IBM System Storage DS8000and DS6000 series. (Yes, BarryB, IBM still sells the DS6000!) The DS6000 was specifically designed with the System i and smaller System z mainframes in mind, and in that niche does very well. Fortunately, as I mentioned in my February post [Getting off the island - the new i5/OS V6R1], IBM has now used virtualization, in the form of the VIOS logical partition, to allow i5/OS systems to attach to standard 512-byte block devices, greatly expanding the storage choices for our clients.
(Side note: SNW happens twice per year, so the challenge is having something new and fresh to talk about each time. While Andy Monshaw, General Manager of IBM System Storage, highlighted some of the many emerging technologies in his keynote address, IBM shipped on many of them prior to his last appearance in October 2007: thin provisioning in the IBM System Storage N series, deduplication in the IBM System Storage N series Advanced Single Instance Storage (A-SIS) feature, and Solid State Disk (SSD) drives in the IBM BladeCenter HS21-XM models. Of course, not everyone buys IBM gear the first day it is available, and IBM is not the only vendor to offer these technologies. My point is that for many people, these are still not yet deployed in their own data center, and so they are still in the future for them. However, since these IBM deliveries happened more than six months ago, they're old news in the eyes of the SNW attendees. While those who follow IBM closely would know that, others like[Britney Spears] may not.)
Back in the 1990s, when IBM was developing the IBM SAN Volume Controller (SVC), we generically called the managed disk arrays that were being virtualized by the SVC as "low-cost RAID brick" or LCRB. The IBM DS3400 is a good example of this. However, as we learned, SVC is not just for LCRB, it adds value in front of all kinds of disk systems, including the not-so-low-cost EMC DMX and IBM DS8000 disk systems. ISE might make a reasonable back-end managed disk device for IBM SVC to virtualize. This gives you the new cool features of Xiotech's ISE, with IBM SVC's faster performance, more robust functionality and advanced copy services.
Next week, I'll be in South America in meetings with IBM Business Partners and storage sales reps.
This is a reasonable question. Since Invista 2.0 came out months ago in August, and Invista 2.1 is rumored to be out by end of this month, why put out a press release now, rather than just wait a few weeks? Thesignificant part of this announcement was that EMC finally has their first customer reference.To be fair, getting a customer to agree to be a reference is difficult for any vendor. Some non-profitsand government agencies have rules against it, and some corporations just don't want to be bothered byjournalists, or take phone calls from other prospective customers. I suspect EMC wanted to put the good folks from Purdue University in front of the cameras and microphones before they:
In Moore's terminology, Purdue University would be a "technology enthusiast", interested in exploring the technologyof the EMC Invista. Universities by their very nature often see themselves as early adopters, willing to take big risks in hopes to reap big rewards. The chasm happens later, when there are a lot of early adopters, all willing to be reference accounts. The mainstream market--shown here as pragmatists, conservatives, and skeptics-- are unwillingto accept reference claims from early adopters, searching instead for moderate gains from minimal risks. They prefer references from customers that are similar in size and industry. Whether a vendor can get a product to cross this chasm is the focus of the book.
Why "SAN" virtualization?
Technically, Invista is "storage" virtualization, not "SAN" virtualization. Virtualizationis any technology that makes one set of resources look and feel like a different setof resources, preferably with more desirable characteristics. You can virtualizeservers, SANs, and storage resources.
Virtual SAN (VSAN) technology, supported bythe Cisco MDS 9500 Series Multilayer Director Switch, partitions a single physical SAN into multipleVSANs, allowing different business functions and requirements to share a common physical infrastructure.
How does Invista advance Cisco's VSAN functionality? It doesn't, but that doesn't makethe title a falsehood, or the press release by association full of lies.If you read the entire press release, EMCcorrectly states that Invista is "storage" virtualization. Some storagevirtualization products, like EMC Invista and IBM System Storage SAN Volume Controller (SVC), require a SAN as a platform for which to perform their magic.Marketing people might use the term "SAN" torefer not just the network gear that provides the plumbing, but also to include the storage devices that are attached to the SAN. In that light, theuse of "SAN virtualization" can be understood in the title.
More importantly, it appears that EMC no longer requires that you purchase new SAN equipment from themwith Invista. When the Invista first came out, it cost over a quarter-million US dollars to cover thecost of the intelligent switches, but with the price drop to $100K, I imagine this means theyassume everyone has an appropriately-supported intelligent switch already deployed.
Why this architecture?
In his post [Storage Virtualization and Invista 2.0], EMC blogger ChuckH does a fair job explaining why EMC went in this direction for Invista, and how it is different thanother storage virtualization products.
Most storage virtualization products are cache-based. The world's first disk storagevirtualization product, the IBM 3850 Mass Storage System, introduced in 1974, and thefirst tape virtualization product, the IBM 3494 Virtual tape Server, introduced in 1997, bothused disk cache in front of tape storage. Later virtualization products, like IBM SVC and HDS USP-V, use DRAM memory cache in front of disk storage, but the concept is the same.People are comfortable with cache-based solutions, because the technology is matureand well proven in the marketplace, and excited and delighted that these can offer the following features in a mixed heterogeneous disk environment:
instantaneous point-in-time copy
None of these features are provided by Invista, as there is no cache in the switch. Instead,Invista is a "packet cracker"; it cracks open each FCP packet, inspects and modifies the contents, then passes theFCP packet along to the appropriate storage device. This process slows down each read andwrite by some amount, perhaps 20 microseconds. The disadvantage of slowing down every readand write is offset by having other benefits, like non-disruptive data migration.
To compensate for Invista's inability to provide these features,EMC offers a second solution called EMC RecoverPoint, which is an in-band cache-based appliancesimilar in design to SVC, but maps all virtual disks one-to-one to physical disks. It offersremote distance asynchronous mirroring between heterogeneous devices.EMC supports RecoverPoint in front of Invista, but if you are considering buying bothto get the combined set of features, you might as well buy an IBM SVC or HDS USP-V instead,in one system, rather than two, which is much less complicated. IBM SVC and HDS USP-Vhave both "crossed the chasm" having sold thousands of units to every type and size of customer.
Hopefully, this answers the questions you might have about EMC Invista.
Continuing my week in Chicago, for the IBM Storage Symposium 2008, I attended several sessions intended to answer the questions of the audience.
In an effort to be cute, the System x team have a "Meet the xPerts" session at their System x and BladeCenter Technical Conference, so the storage side decided to do the same. Traditionally, these have been called "Birds of a Feature", "Q&A Panel", or "Free-for-All". They allow anyone to throw out a question, and have the experts in the room, either
IBM, Business Partner or another client, answer the question from their experience.
Meet the Experts - Storage for z/OS environments
Here were some of the questions answered:
I've seen terms like "z/OS", "zSeries" and "System z" used interchangeably, can you help clarify what this particular session is about?
IBM's current mainframe servers are all named "System z", such as our System z9 or System z10. These replace the older zSeries models of hardware. z/OS is one of the six operating systems that run on this hardware platform. The other five are z/VM, z/VSE, z/TPF, Linux and OpenSolaris. The focus of this session will be storage attached and used for z/OS specifically, including discussions of Omegamon and DFSMS software products.
What can we do to reduce our MIPS-based software licensing costs from our third party vendors?
Consider using IBM System z Integrated Information Processor
What about 8 Gbps FICON?
IBM has already announced
[FICON Express8] host bus adapter (HBA) cards, that will auto-negotiate to 4Gbps and 2Gbps speeds. If you don't need full 8Gbps speed now, you can
still get the Express8 cards, but put 4/2/1 Gbps SFP ports instead. Currently, LongWave (LW) is only supported to 4km at 8Gbps speed.
I want to use Global Mirror for my DS8100 to my remote DS8100, but also make test copies of my production data to
an older ESS 800 I have locally. Any suggestions? Yes, consider using FlashCopy to simplify this process.
I have Global Mirror (GM) running now successfully with DSCLI, and now want to deploy IBM Tivoli Storage Productivity Center for Replication. Is that possible? Yes, Productivity Center for Replication will detect existing GM relationships, and start managing them.
I have already deployed HyperPAV and zHPF, is there any value in getting Solid-State Drives as well?
HyperPAV and zHPF impact CONN time, but SSD impacts DISC time, so they are mutually complementary.
How should I size my FlashCopy SE pool? SE refers to "Space Efficient", which stores only the changes
between the source and destination copies of each LUN or CKD volume involved. General recommendation is to start with 20 percent and adjust accordingly.
How many RAID ranks should I configure per DS8000 extent pool? IBM recommends 4 to 8 ranks per pool.
Meet the Experts: Storage for Linux, UNIX and Windows distributed systems
This session was focused on storage systems attached to distributed servers, as well as products from Tivoli used to manage them. Here were some of the questions answered:
When we migrated from Tivoli Storage Manager v5 to v6, we lost our favorite "Operational Reporting" tool. How can we get TOR back? You now get the new Tivoli Common Reporting tool.
How can we identify appropriate port distribution for multiple SVC node pairs for load balancing?
IBM Tivoli Storage Productivity Center v4.1 has hot-spot analysis with recommendations for Vdisk migrations.
We tried TotalStorage Productivity Center way back when, but the frequent upgrades were killing us. How has it been lately? It has been much more stable since v3.3, and completely renamed to Tivoli Storage Productivity Center to avoid association with versions 1 and 2 of the predecessor product. The new "lightweight agents" feature of v4.1 resolve many of the problems you were experiencing.
We have over 1600 SVC virtual disks, how do we handle this in IBM Tivoli Storage Productivity Center? Use the Filter capability in combination with clever naming conventions for your virtual disks.
How can we be clever when we are limited to only 15 characters? Ok. We understand.
We are currently using an SSPC with Windows 2003 and 2GB memory, but we are only using the Productivity Center for Replication feature of it. Can we move the DB2 database over to a Windows 2008 server with 4GB of memory?
Consider using the IBM Tivoli Storage Productivity Center for Replication software instead of SSPC for special
circumstances like this.
We love the XIV GUI, how soon will all other IBM storage products have it also? As with every acquisition,
IBM evaluates if there are technologies from new products that can be carried back to existing products.
We are currently using 12 ports on our existing XIV, and love it so much we plan to buy a second frame, but are concerned about consuming another 12 ports on our SAN switch. Any suggestions? Yes, use only six ports per frame. Just because you have more ports, doesn't mean you are required to use them.
We have heard there are concerns from the legal community about using deduplication technology, any ideas how to address that?
Nobody here in the room is a lawyer, and you should consult legal counsel for any particular situation.
None of the IBM offerings intended for non-erasable, non-rewriteable (NENR) data retention records (DR550, WORM tape, N series SnapLock) support dedupe today, and none of IBM's deduplication offerings (TS7650,N series A-SIS,TSM) make any claims for fit-for-purpose for compliance regulatory storage. However, be assured that all of IBM's dedupe technology involves byte-for-byte comparisons so that you never lose any data due to false hash collisions. For all IBM compliance storage, what you write will be read back in the correct sequence of ones and zeros.
Now that IBM XIV has proven that 1TB SATA are safe for high-end tier-1 enterprise class use, we extended DS8000 support to include SATA support also. DS8000 supports RAID-6 and RAID-10 for these.
Intelligent Write Caching
IBM Research conducts extensive investigations into improved algorithms for cache management. Intelligent Write Caching boosts performance for both temporal and spatial locality.
Remote Pair FlashCopy®
This allows you to FlashCopy volume A to volume B, with Volume B remotely mirrored to Volume C at a secondary location, via Metro Mirror. This allows you to have a consistent copy of your data at both locations.
IBM was the first in the industry to deliver tape-drive encryption, so it makes sense that IBM is also the first in the industry to deliver disk-drive encryption. These are 15K rpm drives in standard 146GB, 300GB and 450GB capacities. As with tape, encrypting at the disk device eliminates the huge overhead from server-based encryption methods.
Solid State Drive (SSD)
You can also have Solid State Disk drives in your DS8000, in 73GB and 146GB capacities, protected by RAID-5.If you are wondering what data to put on these much-faster drives, IBM has taken the work and worry out by havingintelligence in DB2 to optimize what gets placed on SSD to get the most performance improvement.
IBM System Storage XIV
Continuing the incredible marketplace excitement over its Cloud-Opimized Storage[XIV series], IBM now has announced[new capacity options]. The IBM XIV R2 that we announced last August 2008 was a fixed 15 module configuration. In thenew configurations, you can start with as little as six modules, representing a 40% partial rack of the originalfull model. Here is a table that shows the details:
Useable Capacity (TB)
Fibre Channel Ports
Cache Memory (GB)
IBM System Storage N series
And last, but not least, we have two new models in IBM's[N6000 series].The [N6060]has model A12 (single controller) and model A22 (dual controller). These are disk-less controllers thatyou can configure in either appliance mode or gateway mode. In appliance mode, you can attachdisk drawers such as the EXN1000, EXN2000 or EXN4000. In gateway mode, you attach external disk systems, suchas the IBM DS8000 or XIV above.
It's ruggedized to handle earthquakes. IBM brings a feature that we've had for a while on other disk systems to the N series with a collection of bolts and anchors to secure the rack from physical tremors.
It's instrumented for IBM Active Energy Manager, a component of IBM Systems Director. New iPDUs are designed to help measure and monitor energy management components. As companies get more concerned about thefate of the planet, monitoring energy consumption can help reduce carbon footprint.
I'll cover the rest of the announcements tomorrow!
Array-based replication does have drawbacks; all externalised storage becomes dependent on the virtualising array. This makes replacement potentially complex. To date, HDS have not provided tools to seamlessly migrate away from one USP to another (as far as I am aware). In addition, there's the problem of "all your eggs in one basket"; any issue with the array (e.g. physical intervention like fire, loss of power, microcode bug etc) could result in loss of access to all of your data. Consider the upgrade scenario of moving to a higher level of code; if all data was virtualised through one array, you would want to be darn sure that both the upgrade process and the new code are going to work seamlessly...
The final option is to use fabric-based virtualisation and at the moment this means Invista and SVC. SVC is an interesting one as it isn't an array and it isn't a fabric switch, but it does effectively provide switching capabilities. Although I think SVC is a good product, there are inevitably going to be some drawbacks, most notably those similar issues to array-based virtualisation (Barry/Tony, feel free to correct me if SVC has a non-disruptive replacement path).
I would argue that the IBM System Storage SAN Volume Controller (SVC) is more like the HDS USP, and less like the Invista. Both SVC and USP provide a common look and feel to the application server, both provide additional cache to external disk, both are able to provide a consistent set of copy services.
IBM designed the SVC so that upgrades can occur non-disruptively. You can replace the hardware nodes, one node at a time, while the SVC system is up and running, without disruption to reading and writing data on virtual disk. You can upgrade the software, one node at a time, while the SVC system is up and running, without disruption to reading and writing data on virtual disk. You can upgrade the firmware on the managed disk arrays behind the SVC, again, without disruption to reading and writing data on virtual disk.
More importantly, SVC has the ultimate "un-do" feature. It is called "image mode". If for any reason you want to take a virtual disk out of SVC management, you migrate over to an "image mode" LUN, and then disconnect it from SVC. The "image mode" LUN can then be used directly, with all the file system data in tact.
I define "virtualization" as technology that makes one set of resources look and feel like a different set of resources with more desirable characteristics. For SVC, the more desirable characteristics include choice of multi-pathing driver, consistent copy services, improved performance, etc. For EMC Invista, the question is "more desirable for whom?" EMC Invista seems more designed to meet EMC's needs, not its customers. EMC profits greatly from its EMC PowerPath multi-pathing driver, and from its SRDF copy services, so it appears to have designed a virtualization offering that:
Continuesthe use of EMC Powerpath as a multi-pathing driver. SVC supports driversthat are provided at no charge to the customer, as well as those built-in to each operating system like MPIO.
and, continuesthe use of Array-based copy services like SRDF of the underlying disk. SVC providesconsistent copy services regardless of storage vendor being managed.
A post from Dan over at Architectures of Control explains the anti-social nature of public benches. City planners, in an effort to discourage homeless people from sleeping on benches in parks or sidewalks, design benches that are so uncomfortableto use, that nobody uses them. These included benches made of metal that are too hot or too cold during certainmonths, benches slanted at an angle that dump you on the ground if you lay down, or benches that have dividers sothat you must be in an upright seated position to use.
This is not a disparagement of split-path switch-based designs. Rather, EMC's specific implementation appears to be designed for it to continuevendor lock-in for its multi-pathing driver, continuevendor lock-in for its copy services when used with EMC disk, and only provide slightly improved data migration capability for heterogeneous storage environments. Other switch-based solutions, such as those from Incipient or StoreAge, had different goals in mind.
Sadly, my IBM colleague BarryW and I have probably spent more words discussing Invista than all eleven EMC bloggers combined this year. While everyone in the industry is impressed how often EMC can sell "me, too" products with an incredibly large marketing budget, EMC appears not to have set aside funds for the Invista.
If a customer could design the ideal "storage virtualization" solution that would provide them the characteristics they desire the most from storage resources, it would not be anything like an Invista. While there are pros and cons between IBM's SVC and HDS's TagmaStore offerings, the reason both IBM and HDS are the market leaders in storage virtualization is because both companies are trying to provide value to the customer, just in different ways, and with different implementations.
Yesterday, I started this week's topic discussing the various areas of exploration to helpunderstand our recent press release of the IBM System Storage SAN Volume Controller and itsimpressive SPC-1 and SPC-2 benchmark results that ranks it the fastest disk system in the industry.
Some have suggested that since the SVC has a unique design, it should be placed in its own category,and not compared to other disk systems. To address this, I would like to define what IBM meansby "disk system" and how it is comparable to other disk systems.
When I say "disk system", I am going to focus specifically on block-oriented direct-access storage systems, which I will define as:
One or more IT components, connected together, that function as a whole, to serve as a target forread and write requests for specific blocks of data.
Clarification: One could argue, and several do in various comments below, that there are other typesof storage systems that contain disks, some that emulate sequential access tape libraries, some that emulate file-systems through CIFS or NFS protocols, and some that support thestorage of archive objects and other fixed content. At the risk of looking like I may be including or excluding such to fit my purposes, I wanted to avoid apples-to-orangescomparisons between very different access methods. I will limit this exploration to block-oriented, direct-access devices. We can explore these other types of storage systems in later posts.
People who have been working a long time in the storage industry might be satisfied by this definition, thinkingof all the disk systems that would be included by this definition, and recognize that other types of storage liketape systems that are appropriately excluded.
Others might be scratching their heads, thinking to themselves "Huh?" So, I will provide some background, history, and additional explanation. Let's break up the definition into different phrases, and handle each separately.
read and write requests
Let's start with "read and write requests", which we often lump together generically as input/output request, or just I/O request. Typically an I/O request is initiated by a host, over a cable or network, to a target. The target responds with acknowledgment, data, or failure indication. A host can be a server, workstation, personal computer, laptop or other IT device that is capable of initiating such requests, and a target is a device or system designed to receive and respond to such requests.
(An analogy might help. A woman calls the local public library. She picks up the phone, and dials the phone number of the one down the street. A man working at the library hears the phone ring, answers it with "Welcome to the Public Library! How can I help you?" She asks "What is the capital city of Ethiopia?" and replies "Addis Ababa." and hangs up. Satisfied with this response, she hangs up. In this example, the query for information was the I/O request, initiated by the lady, to the public library target)
Today, there are three popular ways I/O requests are made:
CCW commands over OEMI, ESCON or FICON cables
SCSI commands over SCSI, Fibre Channel or SAS cables
SCSI commands over Ethernet cables, wireless or other IP communication methods
specific blocks of data
In 1956, IBM was the first to deliver a disk system. It was different from tape because it was a "direct access storage device" (the acronym DASD is still used today by some mainframe programmers). Tape was a sequential media, so it could handle commands like "read the next block" or "write the next block", it could not directly read without having to read past other blocks to get to it, nor could it write over an existing block without risking overwriting the contents of blocks past it.
The nature of a "block" of data varies. It is represented by a sequence of bytes of specific length. The length is determined in a variety of ways.
CCW commands assume a Count-Key-Data (CKD) format for disk, meaning that tracks are fixed in size, but that a track can consist of one or more blocks, and can be fixed or variable in length. Some blocks can span off the end of one track, and over to another track. Typical block sizes in this case are 8000 to 22000 bytes.
SCSI commands assume a Fixed-Block-Architecture (FBA) format for disk, where all blocks are the same size, almost always a power of two, such as 512 or 4096 bytes. A few operating systems, however, such as i5/OS on IBM System i machines, use a block size that doesn't follow this power-of-two rule.
one or more IT components
You may find one or more of the following IT components in a disk system:
motorized platter(s) covered in magnetic coating with a read/write head to move over its surface. These are often referred to as Hard Disk Drive (HDD) or Disk Drive Modules (DDM), and are manufacturedby companies like Seagate or Hitachi Global Storage Technologies.
A set of HDD can be accessed individually, affectionately known as JBOD for Just-a-bunch-of-disk, or collectively in a RAID configuration.
Memory can act as the high-speed cache in front of slower storage, or as the storage itself. For example, the solid state disk that IBM announced last week is entirely memory storage, using Flash technology.
Lately, there are two popular packaging methods for disk systems:
Monolithic -- all the components you need connected together inside a big refrigerator-sized unit, with options to attach additional frames. The IBM System Storage DS8000, EMC Symmetrix DMX-4 and HDS TagmaStore USP-V all fit this category.
Modular -- components that fit into standard 19-inch racks, often the size of the vegetable drawer inside a refrigerator, that can be connected externally with other components, if necessary, to make a complete disk system. The IBM System Storage DS6000, DS4000, and DS3000 series, as well as our SVC and N series, fall into this category.
Regardless of packaging, the general design is that a "controller" receives a request from its host attachment port, and uses its processors and cache storage to either satisfy the request, or pass the request to the appropriate HDD,and the results are sent back through the host attachment port.
In all of the monolithic systems, as well as some of the modular ones, the controller and HDD storage are contained in the same unit. On other modular systems, the controller is one system, and the HDD storage is in a separate system, and they are cabled together.
serve as a target
The last part is that a disk system must be able to satisfy some or all requests that come to it.
(Using the same analogy used above, when the lady asked her question, the guy at the public library knew the answer from memory, and replied immediately. However, for other questions, he might need to look up the answer in a book, do a search on the internet, or call another library on her behalf.)
Some disk systems are cache-only controllers. For these, either the I/O request is satisfied as a read-hit or write-hit in cache, or it is not, and has to go to the HDD. The IBM DS4800 and N series gateways are examples of this type of controller.
Other systems may have controller and disk, but support additional disk attachment. In this case, either the I/O request is handled by the cache or internal disk, or it has to go out to external HDD to satisfy the request. IBM DS3000 series, DS4100, DS4700, and our N series appliance models, all fall into this category.
So, the SAN Volume Controller is a disk system comprising of one to four node-pairs. Each node is a piece of IT equipment that have processors and cache. These node-pairs are connected to a pair of UPS power supplies to protect the cache memory holding writes that have not yet been de-staged. The combination of node-pairs and UPS acting as a whole, is able to serve as a target to SCSI commands sent over Fibre Channel cables on a Storage Area Network (SAN). To read some blocks of data, it uses its internal cache storage to satisfy the request, and for others, it goes out to external disk systems that contain the data required. All writes are satisfied immediately in cache on the SVC, and later de-staged to external disk when appropriate.
As of end of 2Q07, having reached our four-year anniversary for this product, IBM has sold over 9000 SVC nodes, which are part of more than 3100 SVC disk systems. These things are flying off the shelves, clocking in a 100% YTY growth over the amount we sold twelve months ago. Congratulations go to the SVC development team for their impressive feat of engineering that is starting to catch the attention of many customers and return astounding results!
So, now that I have explained why the SVC is considered a disk system, tomorrow I'll discuss metrics to measure performance.
It's Tuesday, which means IBM makes its announcements. We had several for the IBM System Storage product line. Here's a quick recap.
The IBM System Storage DS3000 now offers DC power models.New DC powered models of the DS3200, DS3400, and EXP3000 are well suited for Telco industry environments, as theseare NEBS and ETSI compliant and are powered by an industry standard 48 volt DC power source.
Also, the IBM System Storage N series now supports750GB SATA drives available for the EXN1000 drawer.
IBM Virtualization Engine TS7740now supports 3-cluster grids. Unlike 3-way replication on disk mirroring, such as IBM Metro/Global Mirror for the DS8000 that enforces a primary, secondary and tertiary copy, the grid implementation of TS7740 tape virtualization allows for any-to-any mirroring. Existing standalone TS7740 clusters can be converted to grid-enabled. A "Copy Export" feature allows virtual tapes to be exported onto physical tape. And in keeping with our theme of "enabling business flexibility", performance throughput can now be purchased in 100 MB/sec increments, up to 600 MB/sec, to match your workload bandwidth requirements.
The IBM System Storage TS1120drives installed in the IBM System Storage™ TS3400 Tape Library can now be attached to System z platforms using the IBM System Storage™ TS1120 Tape Controller. Before this, the TS3400 could only be attached to UNIX, Windows and Linux systems.
The IBM System StorageTS2230 Express is offered as an external stand-alone or rack-mountable unit. This model incorporates the new LTO IBM Ultrium 3 Serial Attached SCSI (SAS) Half-High Tape Drive, and a 3 Gbps single port SAS interface for a connection to a wide spectrum of distributed system servers that support Microsoft Windows and Linux systems.
IBM has added theCisco MDS 9124 for IBM System Storageentry-level fabric switch as an Express offering and part of the IBM Express Advantage Program. Express offerings are specifically created for mid-market companies and are well suited for workgroup storage applications like e-mail serving, collaborative databases and web serving. They bring enterprise-class performance, scalability and features to small and medium-sized companies and are easy to use, highly scalable, and cost-effective.This will make it easier for IBM Business Partners to provide fabric switch connectivity for:
Storage consolidation solutions with IBM System Storage™ DS4000 Express disk arrays, especially the DS4700 Express.
Backup / restore solutions with IBM System Storage™ TS3000 Tape Libraries, such as the TS3200.
Archive and Retention
Ordering large configurations of the IBM System Storage Grid Access Manager just got a lot easier.New features enable configurations greater than 500 TB to be submitted as a single order. No change in the actualproduct, just an improvement in the ordering process.
For System p and System i servers, the IBM 3996 Optical library now supports Gen 2 60GB optical cartridges. These can be read/write or WORM cartridges.
I'm off to Denver, Colorado this week. I hope it is cooler there than it is down here in Tucson, Arizona.
Wrapping up this week's exploration on disk system performance, today I willcover the Storage Performance Council (SPC) benchmarks, and why I feel they are relevant to help customers make purchase decisions. This all started to address a comment from EMC blogger Chuck Hollis, who expressed his disappointment in IBM as follows:
You've made representations that SPC testing is somehow relevant to customers' environments, but offered nothing more than platitudes in support of that statement.
Apparently, while everyone else in the blogosphere merely states their opinions and moves on,IBM is held to a higher standard. Fair enough, we're used to that.Let's recap what we covered so far this week:
Monday, I explained how seemingly simple questions like "Which is the tallestbuilding?" or "Which is the fastest disk system?" can be steeped in controversy.
Tuesday, I explored what constitutes a disk system. While there are special storage systemsthat include HDD that offer tape-emulation, file-oriented access, or non-erasable non-rewriteable protection,it is difficult to get apples-to-apples comparisions with storage systems that don't offer these special features.I focused on the majority of general-purpose disk systems, those that are block-oriented, direct-access.
Today, I will explore ways to apply these metrics to measure and compare storageperformance.
Let's take, for example, an IBM System Storage DS8000 disk system. This has a controller thatsupports various RAID configurations, cache memory, and HDD inside one or more frames.Engineers who are testing individual components of this system might run specifictypes of I/O requests to test out the performance or validate certain processing.
100% read-hit, this means that all the I/O requests are to read data expectedto be in the cache.
100% read-miss, this means that all the I/O requests are to read data expectedNOT to be in the cache, and must go fetch the data from HDD.
100% write-hit, this means that all the I/O requests are to write data into cache.
100% write-miss, this means that all the I/O requests are to bypass the cache,and are immediately de-staged to HDD. Depending on the RAID configuration, this can result in actually reading or writing several blocks of data on HDD to satisfy thisI/O request.
Known affectionately in the industry as the "four corners" test, because you can show them on a box, with writes on the left, reads on the right,hits on the top, and misses on the bottom.Engineers are proud of these results, but these workloads do notreflect any practical production workload. At best, since all I/O requests are oneof these four types, the four corners provide an expectation range from the worst performance (most often write-missin the lower left corner)and the best performance (most often read-hit in the upper right corner) you might get with a real workload.
To understand what is needed to design a test that is more reflective of real business conditions,let's go back to yesterday's discussion of fuel economy of vehicles, with mileage measured in miles per gallon.The How Stuff Works websiteoffers the following description for the two measurements taken by the EPA:
The "city" program is designed to replicate an urban rush-hour driving experience in which the vehicle is started with the engine cold and is driven in stop-and-go traffic with frequent idling. The car or truck is driven for 11 miles and makes 23 stops over the course of 31 minutes, with an average speed of 20 mph and a top speed of 56 mph.
The "highway" program, on the other hand, is created to emulate rural and interstate freeway driving with a warmed-up engine, making no stops (both of which ensure maximum fuel economy). The vehicle is driven for 10 miles over a period of 12.5 minutes with an average speed of 48 mph and a top speed of 60 mph.
Why two different measurements? Not everyone drives in a city in stop-and-go traffic. Having only one measurement may not reflect the reality that you may travel long distances on the highway. Offering both city and highway measurements allows the consumers to decide which metric relates closer to their actual usage.
Should you expect your actual mileage to be the exact same as the standardized test?Of course not. Nobody drives exactly 11 miles in the city every morning with 23 stops along the way,or 10 miles on the highway at the exact speeds listed.The EPA's famous phrase "your mileage may vary" has been quickly adopted into popular culture's lexicon. All kinds of factors, like weather, distance, anddriving style can cause people to get better or worse mileage than thestandardized tests would estimate.
Want more accurate results that reflect your driving pattern, in specific conditions that you are most likely to drive in? You could rentdifferent vehicles for a week and drive them around yourself, keeping track of whereyou go, and how fast you drove, and how many gallons of gas you purchased, so thatyou can then repeat the process with another rental, and so on, and then use yourown findings to base your comparisons. Perhaps you find that your results are always20% worse than EPA estimates when you drive in the city, and 10% worse when you driveon the highway. Perhaps you have many mountains and hills where you drive, you drive too fast, you run the Air Conditioner too cold, or whatever.
If you did this with five or more vehicles, and ranked them best to worstfrom your own findings, and also ranked them best to worst based on the standardizedresults from the EPA, you likely will find the order to be the same. The vehiclewith the best standardized result will likely also have the best result from your ownexperience with the rental cars. The vehicle with the worst standardized result willlikely match the worst result from your rental cars.
(This will be one of my main points, that standardized estimates don't have to be accurate to beuseful in making comparisons. The comparisons and decisions you would make with estimatesare the same as you would have made with actual results, or customized estimates based on current workloads. Because the rankings are in the same order, they are relevant and useful for making decisions based on those comparisons.)
Most people shopping around for a new vehicle do not have the time or patience to do this with rental cars. Theycan use the EPA-certified standardized results to make a "ball-park" estimate on how much they will spendin gasoline per year, decide only on cars that might go a certain distancebetween two cities on a single tank of gas, or merely to provide ranking of thevehicles being considered. While mileage may not be the only metric used in making a purchase decision, it can certainly be used to help reduce your consideration setand factor in with other attributes, like number of cup-holders, or leather seats.
In this regard, the Storage Performance Council has developed two benchmarks that attempt to reflect normal business usage, similar to "City" and "Highway" driving measurements.
SPC-1 consists of a single workload designed to demonstrate the performance of a storage subsystem while performing the typical functions of business critical applications. Those applications are characterized by predominately random I/O operations and require both queries as well as update operations. Examples of those types of applications include OLTP, database operations, and mail server implementations.
SPC-2 consists of three distinct workloads designed to demonstrate the performance of a storage subsystem during the execution of business critical applications that require the large-scale, sequential movement of data. Those applications are characterized predominately by large I/Os organized into one or more concurrent sequential patterns. A description of each of the three SPC-2 workloads is listed below as well as examples of applications characterized by each workload.
Large File Processing: Applications in a wide range of fields, which require simple sequential process of one or more large files such as scientific computing and large-scale financial processing.
Large Database Queries: Applications that involve scans or joins of large relational tables, such as those performed for data mining or business intelligence.
Video on Demand: Applications that provide individualized video entertainment to a community of subscribers by drawing from a digital film library.
The SPC-2 benchmark was added when people suggested that not everyone runs OLTP anddatabase transactional update workloads, just as the "Highway" measurement was addedto address the fact that not everyone drives in the City.
If you are one of the customers out there willing to spend the time and resources to do your own performance benchmarking, either at your own data center, or with theassistance of a storage provider, I suspect most, if not all, the major vendors(including IBM, EMC and others), and perhaps even some of the smaller start-ups, would be glad to work with you.
If you want to gather performance data of your actual workloads, and use this to estimate how your performance might be with a new or different storage configuration, IBMhas tools to make these estimates, and I suspect (again) that most, if not all, of theother storage vendors have developed similar tools.
For the rest of you who are just looking to decide which storage vendors to invite on your next RFP, and which products you might like to investigate that matchthe level of performance you need for your next project or application deployment,than the SPC benchmarks might help you with this decision. If performance is importantto you, factor these benchmark comparisons with the rest of the attributes you arelooking for in a storage vendor and a storage system.
In my opinion, I feel that for some people, the SPC benchmarks provide some value in this decision making process. They are proportionally correct, in that even ifyour workload gets only a portion of the SPC estimate, that storage systems withfaster benchmarks will provide you better performance than storage systems with lower benchmark results. That is why I feel they can be relevant in makingvalid comparisons for purchase decisions.
Hopefully, I have provided enough "food for thought"on this subject to support why IBM participates in the Storage Performance Council, why the performance of the SAN Volume Controller can be compared to the performanceof other disk systems, and why we at IBM are proud of the recent benchmark results in our recent press release.
With all the announcements we had in June, it is easy for some of the more subtle enhancements to get overlooked. While I was at Orlando for the IBM Edge conference, I was able to blog about some of the key featured announcements. Then, later, when I got back from Orlando to Tucson, I was able to then blog about [More IBM Storage Announcements]. For IBM's Scale-Out Network Attach Storage (SONAS), I had simply:
"SONAS v1.3.2 adds support for management by the newly announced IBM Tivoli Storage Productivity Center v5.1 release. Also, IBM now officially supports Gateway configurations that have the storage nodes connected to XIV or Storwize V7000 disk systems. These gateway configurations offer new flexible choices and options for our ever-expanding set of clients."
In my defense, IBM numbers its software releasees with version.release.modification, so 1.3.2 is Version 1, Release 3, Modification 2. Generally, modification announcements don't get much attention. The big announcement for v1.3.0 of SONAS happened last October, see my blog post [October 2011 Announcements - Part I] or
the nice summary post [IBM Scale-out Network Attached Storage 1.3.0] from fellow blogger Roger Luethy.
Here is a diagram showing the three configurations of SONAS.
I have covered the SONAS Appliance model in depth in previous blogs, with options for fast and slow disk speeds, choice of RAID protection levels, a collection of enterprise-class software features provided at no additional charge, and interfaces to support a variety of third party backup and anti-virus checking software.
The basics haven't changed. The SONAS appliance consists of 2 to 32 interface nodes, 2 to 60 storage nodes, and up to 7,200 disk drives. The maximum configuration takes up 17 frames and holds 21.6PB of raw disk capacity, which is about 17PB usable space when RAID6 is configured. An interface nodes has one or two hex-core processors with up to 144GB of RAM to offer up to 3.5GB/sec performance each. This makes IBM SONAS the fastest performing and most scalable disk system in IBM's System Storage product line.
I thought I would go a bit deeper on the gateway models. These models support up to ten storage nodes, organized in pairs. The key difference is that instead of internal disk controllers, the storage nodes connect to external disk systems. There is enough space in the base SONAS rack to hold up to six interface nodes, or you can add a second rack if you need more interface nodes for increased performance.
SONAS with XIV gateway
XIV offers a clever approach to storage that allows for incredibly fast access to data on relatively slow 7200 RPM drives. By scattering data across all drives and taking advantage of parallel processing, rebuild times for a failed 3TB drive are less than 75 minutes. Compare that to typical rebuild times for 3TB drives that could take as much as 9-10 hours under active I/O loads!
In the configuration, each pair of storage nodes can connect to external SAN Fabric switches that then connect to one or two XIV storage systems. How simple is that? These can be the original XIV systems that support 1TB and 2TB drives, or the new XIV Gen3 systems that support 400GB Solid-state drives (SSD) and 3TB spinning disk drives. In both cases, you can acquire additional storage capacity as little as 12 drives at a time (one XIV module holds 12 drives).
The maximum configuration of ten XIV boxes could hold 1,800 drives. At 3TB drive per drive, that would be 2.4PB usable capacity.
The SONAS with XIV gateway does not require the XIV devices to be dedicated for SONAS purposes. Rather, you can assign some XIV storage space for the SONAS, and the rest is available for other servers. In this manner, SONAS just looks like another set of Linux-based servers to the XIV storage system. This in effect gives you "Unified Storage", with a full complement of NAS protocols from the SONAS side (NFS, CIFS, FTP, HTTPS, SCP) as well as block-based protocols directly from the XIV (FCP, iSCSI).
SONAS with Storwize V7000 gateway
The other gateway offering is the SONAS with Storwize V7000. Like the SONAS with XIV gateway model, you connect a pair of SONAS storage nodes to 1 or 2 Storwize V7000 disk systems. However, you do not need a SAN Fabric switch in between. You can instead connect the SONAS storage nodes directly to the Storwize V7000 control enclosures.
To acquire additional storage capacity, you can purchase a single drive at a time. That's right. Not 12 drives, or 60 drives, at a time, but one at a time. The Storwize V7000 supports a wide range of SSD, SAS and NL-SAS drives at different sizes, speeds and capacities. The drives can be configured into various RAID protection levels: RAID 0, 1, 3, 5, 6 and 10.
Each Storwize V7000 control enclosure can have up to nine expansion drawers. If you choose the 2.5-inch 24-bay models, you can have up to 480 drives per storage node pair, for a total of 2,400 drives. If you choose the 3.5-inch 12-bay models, you can have up to 240 drives per node pair, 1,200 drives total. At 3TB per drive, this could be 3.6PB of raw capacity. The usable PB would depend on which RAID level you selected. Of course, you don't have to limit yourself all to one size or the other. Feel free to mix 2.5-inch and 3.5-inch drawers to provide different storage pool capabilities.
All three SONAS configurations support Active Cloud Engine. This is a collection of features that differentiate SONAS from the other scale-out NAS wannabees in the marketplace:
Policy-driven Data Placement -- Different files can be directed to different storage pools. You no longer have to associate certain file systems to certain storage technologies.
High-speed Scan Engine -- SONAS can scan 10 million files per minute, per node. These scans can be used to drive data migration, backups, expirations, or replications, for example. It is over 100 times faster than traditional walk-the-directory-tree approaches employed by other NAS solutions.
Policy-driven Migration -- You can migrate files from one storage pool to another, based on age, days since last reference, size, and other criteria. The files can be moved from disk to disk, or move out of SONAS and stored on external media, such as tape or a virtual tape library. A lot of data stored on NAS systems is dormant, with little or no likelihood of being looked at again. Why waste money keeping that kind of data on expensive disk? With SONAS, you can move those files to tape can save lots of money. The files are stubbed in the SONAS file system, so that an access request to a file will automatically trigger a recall to fetch the data from tape back to the SONAS system.
Policy-driven Expiration -- SONAS can help you keep your system clean, by helping you decide what files should be deleted. This is especially useful for things like logs and traces that tend to just hang around until some deletes them manually.
WAN Caching -- This allows one SONAS to act as a "Cloud Storage Gateway" for another SONAS at a remote location connected by Wide Area Network (WAN). Let's say your main data center has a large SONAS repository of files, and a small branch office has a smaller SONAS. This allows all locations to have a "Global" view of the all the interconnected SONAS systems, with a high-speed user experience for local LAN-based access to the most recent and frequently used files.
If you want to learn more, see the [IBM SONAS landing page]. Next week, I will be across the Pacific Ocean in [Taipei], to teach IBM Top Gun class to sales reps and IBM Business Partners. "Selling SONAS" will be one of the topics I will be covering!
We've been quite busy here at the Tucson Executive Briefing Center. I am often asked to explain the relationship between IBM's various storage products. While automakers don't have to explain why they sell sports coupes, pickup trucks and minivans, this analogy does not adequately cover IT storage products. So, I have come up with a new analogy that seems to be a better fit: foundations and flavorings.
All over the world, meals are often comprised of a foundation, perhaps rice, potatoes or pasta, covered with some form of flavoring, sauces, pieces of meat or fish, grated cheese and spices. In Puerto Rico, I had dishes where the foundation was mashed bananas called [plantains]. Sandwich shops often let you pick your choice of bread, the foundation, and then your meats and cheeses, the flavorings.At our local steakhouse,[McMahon's], the menulists a set of steaks, the foundation such as Rib Eye, Filet Mignon, Prime Rib or New York Strip, andvarious flavorings, such as sauces and rubs to cover the steak. Last night, I had the Delmonico steak with the Cristiani sauce consisting of Portobello mushrooms, garlic and aged Romano cheese.
This serves as a useful analogy for IBM's storage strategy. Allowing thefoundations and flavorings to be separately orderable greatly simplifies the selection menu and providesa nearly any-to-any approach to meeting a variety of client needs.Let's take a look at both.
IBM's foundation products are the DS family [DS3000, DS4000, DS5000, DS6000 and DS8000 series], [DS9900 series], and [XIV] for disk, and the TS family [TS1000, TS2000, TS3000] series for tape drives and libraries. In much thesame way you might prefer brown rice instead of white rice, or linguine instead of penne pasta, you might find the attributes of one storagefoundation more attractive based on its performance, scalability and availability features for yourparticular application workloads.
Fellow IBM blogger Barry Whyte discusses SVC at great length on his [Storage Virtualization] blog. Flavoring disk foundation storage with SAN Volume Controller can provide you additionalfeatures and functions, and help improve the scalability, performance or availability characteristics.For example, if you have DS4000, DS8000 and XIV, you might use SVC to provide a consistent methodologyfor asynchronous replication, a form of consistent "flavoring" if you will.
N series Gateways
The [N series gateways] offerflavoring to disk foundation, including unified NAS, iSCSI and FCP protocol host attachment, and application aware capabilities. (As for our IBM N series appliances or "filers", these could be foundational storage behind an SVC, but that's perhaps a topic for another post.)
SoFS provides a global namespace with clustered NAS access to files. This is a blended disk-and-tape solution with built-in backup and Information Lifecycle Management [ILM]. Policies can be used to place different files onto different tiers of storage, automate the movement from tier to tier, including migration to tape, and even expiration when the data is no longer needed.
The [IBM System Storage DR550] provides Non-erasable, Non-rewriteable (NENR) flavoring to storage. While the DR550 comes with internal disk storage, it can front end a tape library filled with WORM cartridges. The DR550 hasbeen paired up with small libraries (TS3200 or TS3310) as well as larger libraries like the TS3500.
The IBM Grid Medical Archive Solution [GMAS] provides a variety of capabilities for storing and accessing medical images, using a blended disk-and-tape approach. This allows hospital and clinicnetworks to provide access for doctors and radiologists from multiple locations.
Many of the flavorings are called "gateways". The IBM TS7650G flavors disk that provides a virtualtape library[VTL] with inline data deduplication capability. Recent performance tests pairing the TS7650G flavoring with XIV foundation storage found this combination to be an excellent match.
Let me know what you think. Does this help you understand IBM's storage strategy and acquisitions? Enteryour comments below.
Well, it's Tuesday again, and that means IBM announcements!
We've got a variety of storage-related items today, so here's my quick recap:
DS5020 and EXP520 disk systems
[IBM System Storage DS5020]
provides the functional replacement for DS4700 disk systems. These are combined controller
and 16 drives in a compact 3U package.
The EXP520 expansion drawer provides additional 16 drives per 3U drawer. A DS5020 can
support upo to six additional EXP520, for a total of 112 drives per system.
The DS5020 supports both 8 Gbps FC as well as 1GbE iSCSI.
New Remote Support Manager (DS-RSM model RS2)
The [IBM System Storage DS-RSM Model
RS2] supports of up to 50 disk systems, any mix of DS3000, DS4000 and DS5000 series.
It includes "call home" support, which is really "email home", sending error alerts to IBM
if there are any problems. The RSM also allows IBM to dial-in to perform diagnostics before
arrival, reducing the time needed to resolve a problem. The model RS2 is a beefier model
with more processing power than the prior generation RS1.
New Ethernet Switches
With the increased interest in iSCSI protocol, and the new upcoming Fibre Channel over
Convergence Enhanced Ethernet (FCoCEE), IBM's re-entrance into the ethernet switch market
has drawn a lot of interest.
The [IBM Ethernet Switch r-
series] offers 4-slot, 8-slot, 16-slot, and 32-slot models. Each slot can handle either
16 10GbE ports, or 48 1GbE ports. This means up to 1,536 ports.
The [c-series] now offers a
24-port model. This is either 24 copper and 4 fiber optic, or 24 fiber optic.
The "hybrid fiber" SFP fiber optic can handle either single or multi-mode, eliminating the
need to commit to one or the other, providing greater data center flexibility.
The [IBM Ethernet Switch B24X]
offers 24 fiber optic (that can handle 10GbE or 1GbE) and 4 copper (10/100/1000 MbE RJ45)
Storage Optimization and Integration Services
[IBM Storage Optimization and
Integration Services] are available. IBM service consultants use IBM's own
Storage Enterprise Resource Planner (SERP) software to evaluate your environment and provide
recommendations on how to improve your information infrastructure. This can be especially
helpful if you are looking at deploying server virtualization like VMware or Hyper-V.
As people look towards deploying a dynamic infrastructure, these new offerings can be a
I've blogged about some of these videos already, but since there are probably a few out there buying the brand new Apple iPhone looking for YouTube videos to play on them, these links might provide some exampleentertainment on your new handheld device.
Next week has "Fourth of July" Independence Day holiday in the USA smack in the middle of the week, so I suspect the blogosphereto quiet down a bit. So whether you are working next week or not, in the USA or elsewhere, take some time to enjoy your friends and family.
Tonight I had dinner with Henry Daboub (an SVC expert from Houston, TX) and some clients, who asked what I would blog about tonight, and I figured it made sense to blog about the SVC.
Hu Yoshida clarifies his position about storage virtualization, including the statement: "As a result they can not provide the availability, scalability, and performance of a DS8300. If they could, there would be no need for a DS8300."
Of course, if humans descended from apes, why are there still apes? Now that we have cars, why are there still trains? But perhaps a better question is: now that there are supercomputers, why are there still mainframe servers?
The issue is the difference between scale-up versus scale-out. Scale-up is making a single box as big and beefy as possible. When the SVC was introduced, the major vendors all had scale-up designs: IBM ESS 800, HDS Lightning, EMC Symmetrix. Like the mainframe, they were for customers that wanted everything in a single monolithic container.
SAN Volume Controller was the result of IBM Research asking the question, if you could put anyone's software (feature and functionality) on anyone's hardware (monolithic scale-up design), what combination would you choose? What if the brains inside today's monolithic systems could be snapped into the another vendor's frame? What if you could run SRDF on an HDS box, or ShadowImage on an IBM box? The surprising response was that most customers would want a single software for consistency, but wanted the option to choose from different vendors hardware, to negotiate the best price of the commodity iron. Based on this feedback, the SVC was born.
The idea was simple, put all the brains in a separate appliance. The appliance would do the non-disruptive migrations, the caching, the striping, and all the copy services. This lets the customer chose then the hardware they want, any mix of FC and ATA disk, from any vendor.
The SVC design was based on IBM's long history in supercomputers. Using the same "scale-out" technology, the power comes not from having it all in one monolithic box, but rather in a design that combines small nodes together. While the cache is not globally shared, the data is shared between node-pairs, and the logical-to-physical mapping is routed around to all nodes in a cluster. Each SVC node talks to each other SVC node through the FCP ports, eliminating the need for additional wiring. For the most part, each node does its own separate work, but when it needs to, they can communicate across, just like nodes in a supercomputer.
Both the SVC and the DS8300 Turbo have better than 99.999 percent availability, based on redundant components designed for no single point of failure (SPOF). IBM has sold thousands of each, and they have been in the field enough time that we can make that claim. There is nothing between scale-up versus scale-out that makes on inherently more available than the other.
Both the SVC and the DS8300 Turbo can scale from as little as a few TB of disk, to hundreds of TB of disk. We have yet to meet a customer that is too big for the SVC. The DS8300 Turbo is able to scale by adding up to four extension frames, but is still considered a single box from a scale-up perspective. From a processor perspective, an 8-node SVC cluster has 16 Intel Xeon processors, and the DS8300 has 8 POWER5+ processors (dual 4-way). The key advantage of scale-out is that you can add capacity to the SVC in smaller increments. Jumping from a DS8100 (dual 2-way) to a DS8300 (dual 4-way) is a big jump.
SVC remains the fastest disk system in the industry, based on both the SPC-1 and SPC-2 benchmarks. The latest model now supports 8GB per node, for a total of 64GB for an 8-node cluster. This can be used for both read and write non-volatile storage. By comparison, DS8300 Turbo has 32GB write non-volatile storage, and up to 256 GB of read-only cache. The SVC is able to do 155,519 IOPS, faster than the 123,030 IOPS for the DS8300, and of course faster than anything from EMC, HDS, HP or Texas Memory Systems. Of course, workloads vary, and there might be some workloads where the 256GB of read-only cache of the monolithic DS8300 is the better choice.
Both SVC and DS8300 Turbo offer FlashCopy (point-in-time copy), Metro Mirror (synchronous) and Global Mirror (asynchronous). SVC provides the additional benefit that it can perform a FlashCopy from one frame to another, and the ability to migrate data seemlessly from one box to another.
Interestingly, IBM has seen a resurgence in both mainframe sales, as well as interest in supercomputers. Both have their place, based on the workload characteristics, and so IBM will continue to offer both modular scale-out designs, as well as monolithic scale-up designs, to meet the different needs of the marketplace.
Lakota Industries made news with the introduction of its [Sarah-Cuda Hunting Bow], named after moose-huntingU.S. Vice President nominee and Governor of Alaska [Sarah Palin]. This has all the same features as their other high-end hunting bows, but is lighter, smaller and available in Pink Camo. This "pink-it-and-shrink-it" move was designed to broaden the market share of hunting bows by reaching out to the needs of women hunters.
Not to be outdone, today, at the Storage Networking World Conference, IBM announced the new IBM System Storage SAN Volume Controller Entry Edition [SVC EE].
The new SVC Entry Edition, available in Flamingo Pink* or traditional Raven Black.
* RPQ required. Default color is Raven Black.
You might be thinking: "Wait! IBM SVC is already the leading storage virtualization product among SMB clients today,why introduce a less expensive model?" With the global economy in the tank, IBM thought it would be nice to help outour smaller SMB clients with this new option.
This new offering is actually a combination of new software (SVC 4.3.1) and new hardware (2145-8A4). Here are thekey differences:
by usable capacity managed, up to 8 PB
by number of disk drives, up to 60 drives
2145-4F2, 8F2, 8F4, 8G4, 8A4
1, 2, 3 or 4 node-pairs, depending on performance requirements
only one node-pair needed
FlashCopy, Metro Mirror and Global Mirror, licensed by subset of capacity used
FlashCopy, Metro Mirror and Global Mirror, but with simplified licensing
The SVC EE is not a "dumbed-down" version of the SVC Classic. It has all the features and functions of theSVC Classic, including thin provisioning with "Space-efficient volumes", Quality of Service (QoS) performance prioritization for more important applications, point-in-time FlashCopy, and both synchronous and asynchronous disk mirroring (Metro and Global Mirror).
While IBM has not yet have SPC-1 benchmarks published, IBM is positioning the SVC EE as roughly 60 percent of the performance, at 60 percent of the list price, compared to a comparable SVC Classic 2145-8G4 configuration. The SVC Classic is already one of the fastest disk systems in the industry. By comparison, the SVC EE is twice as fast as the original SVC 2145-4F2 introduced five years ago.If you outgrow the SVC EE, no problem! The 2145-8A4 can be used in traditional SVC Classic mode, and the SVC EE software can be converted into the SVC Classic software license for upgrade purposes, protecting your originalinvestment!
For those considering an HP EVA 4400 or EMC CX-4 disk system, you might want to look at combining an SVC EE with [IBM System Storage DS3400] disk. The combination offers more features and capabilities, and helps reduce your IT costs at the same time.
And if you are worried you can't afford it right now, IBM Global Financing is offering a ["Why Wait?" world-wide deferral of interest and payments] for 90 days, so you don't have to make your first payment until 2009, applicable to all IBM System Storage products, including the SVC EE, SVC Classic and DS3400 disk systems.
Whew! I am glad that is over. The BarryB circus has left town, he has decided to [move on to other topics], and I am now to clean up the ["circus gold"] leftbehind. I would like to remind everyone that all of these discussions have been about the architecture,not the product. IBM will come out withits own version of a product based on Nextra later in 2008, which may be different than the product that XIV currentlysells to its customers.
RAID-X does not protect against double-drive failures as well as RAID-6, but it's very close
BarryB calls this the "Elephant in the room", that RAID-6 protects better against double-drive failures. I don't dispute that. He also credits me with the term "RAID-X", but I got this directly from the XIV guys. It turns out this was already a term used among academic research circles for [distributed RAID environments]. Meanwhile, Jon Toigo feels the term RAID-X sounds like a brand of bug spray in his post[XIV Architecture: What’s Not to Like?]Perhaps IBM can change this to RAID-5.99 instead.
If you measure risk of a second drive failing during the rebuild or re-replication process ofa first drive failure, you can measure the exposure by multiplying the amount of GB at risk by thenumber of hours that the second failure could occur, resulting in a unit of "GB-hours". Here Ilist best-case rebuild times, your mileage may vary depending on whether other workloads existon the system competing for resources. Notice that 8-disk configurations of RAID-10 and RAID-5for smaller FC disk are in the triple digits, and larger SATA disk in five digits, but that with RAID-X it is only single digits. That is orders of magnitude closer to the ideal.
For each RAID type, the risk is proportional to the square of the individual drive size.Double the drive size causes the risk to be four times greater.This is not the first time this has been discussed. In [Is RAID-5 Getting Old?], Ramskovquotes NetApp's response in Robin Harris' [NetApp Weighs In On Disks]:
...protecting online data only via RAID 5 today verges on professional malpractice.
As disks get older, RAID-6 will not be able to protect against 3-drive failures. A similar chartabove could show the risk to data after the second drive fails and both rebuilds are going on,compared to the risk of a third drive failure during this time. The RAID-X scheme protects muchbetter against 3-drive failures than RAID-6.
Nothing in the Nextra architecture prevents a RAID-6, Triple-copy, or other blob-level scheme
In much the same way that EMC Centera is RAID-5 based for its blobs, there is nothing in the Nextra architecturethat prevents taking additional steps to provide even better protection, using a RAID-6 scheme, making three copiesof the data instead of two copies, or something even more advanced. The current two-copy scheme for RAID-X is betterthan all the RAID-5 and RAID-10 systems out in the marketplace today.
Mirrored Cache won't protect against Cosmic rays, but ECC detection/correction does
BarryB incorrectly states that since some implementations of cache are non-mirrored, that this implies they are unprotected against Cosmic rays. Mirroring does not protect against bit-flips unless both copies arecompared for differences. Unfortunately, even if you compared them, the best you can do is detect theyare different, there is no way of knowing which version is correct.Mirroring cache is normally done to protect uncommitted writes. Reads in cacheare expendable copies of data already written to disk, so ECC detection/correction schemes are adequateprotection. ECC is like RAID for DRAM memory. A single bit-flip can be corrected, multiple bit-flipscan be detected. In the case of detection, the cache copy is discarded and read fresh again from disk.IBM DS8000, XIV and probably most other major vendor offerings use ECC of some kind. BarryB is correctthat some cheaper entry-level and midrange offerings from other vendors might cut corners in this area.I don't doubt BarryB's assertion that the ECC method used in the EMC products may be differently implemented than theECC in the IBM DS8000, but that doesn't mean the IBM DS8000's ECC implementation is flawed.
ECC protection is important for all RAID systems that perform rebuild, and even more importantthe larger the GB-hours listed in the table above.
XIV is designed for high-utilization, not less than 50 percent
I mentioned that the typical Linux, UNIX or Windows LUN is only 30-50 percent full, and perhaps BarryBthought I was referring to the typical "XIV customer". This average is for all disk storage systems connectedto these operating systems, based on IBM market research and analyst reports. The XIV is expected to run at much higher utilization rates, and offers features like "thin provisioning" and "differential snapshot" to make this simple to implement in practice.
Most often, disks don't fail without warning. Usually, they give out temporary errors first, and then fail permanently.The XIV architecture allows for pre-emptive self-repair, initiating the re-replication process after detecting temporary errors, rather than waiting for a complete drive failure.
I had mentioned that this process used "spare capacity, not spare drives" but I was notified that there are three spare drives per system to ensure that there is enough spare capacity, so I stand corrected.
New drives don't have to match the same speed/capacity as the new drives, so three to five years from now, whenit might be hard to find a matching 500GB SATA drive anymore, you won't have to.
No RAID scheme eliminates backups or Business Continuity Planning
The XIV supports both synchronous and asynchronous disk mirroring to remote locations. Backup software willbe able to backup data from the XIV to tape. A double drive failure would require a "recovery action", eitherfrom the disk mirror, or from tape, for the few GB of data that need to be recovered.
A third alternative is to allow end-users to receive backups of their own user-generated content. For example, I have over 15,000 photos uploaded over the past six years to Kodak Photo Gallery, which I use to share with my friends and family. For about $180 US dollars, they will cut DVDs containing all of my uploaded files and send them to me, so that I do not have to worry about Kodak losing my photos.In many cases, if a company or product fails to deliver on its promises, the most you will get is your money back, but for "free services" like HotMail, FreeDrive, FlickR and others, you didn't pay anything in the first place, andthey may point this limitation of liability in the "terms of service".
XIV can be used for databases and other online transaction processing
The XIV will have FCP and iSCSI interfaces, and systems can use these to store any kind of data you want. I mentionedthat the design was intended for large volumes of unstructured digital content, but there is nothing to prevent the use of other workloads. In today's Wall Street Journal article[To Get Back Into the Storage Game, IBM Calls In an Old Foe]:
Today, XIV's Nextra system is used by Bank Leumi, a large Israeli bank, and a few other customers for traditional data-storage tasks such as recording hundreds of transactions a minute.
BarryB, thanks for calling the truce. I look forward to talking about other topics myself. These past two weeks have been exhausting!