I am still wiping the coffee off my computer screen, inadvertently sprayed when I took a sip while reading HDS' uber-blogger Hu Yoshida's post on storage virtualization andvendor lock-in
. This blog appears to be the text version of theirfunny video
While most of the post is accurate and well-stated, two opinions particular caught my eye. I'll be nice and call them opinions, since these are blogs, and always subject to interpretation. I'll put quotes around them so that people will correctly relate these to Hu, and not me.
"Storage virtualization can only be done in a storage controller. Currently Hitachi is the only vendor to provide this."
-- Hu Yoshida
Hu, I enjoy all of your blog entries, but you should know better. HDS is fairly new-comer to the storage virtualization arena, so since IBM has been doing this for decades, I will bring you and the rest of the readers up to speed. I am not starting a blog-fight, just want to provide some additional information for clients to consider when making choices in the marketplace.
First, let's clarify the terminology. I will use 'storage' in the broad sense, including anything that can hold 1's and 0's, including memory, spinning disk media, and plastic tape media. These all have different mechanisms and access methods, based on their physical geometry and characteristics. The concept of 'virtualization' is any technology that makes one set of resources look like another set of resources with more preferable characteristics, and this applies to storage as well as servers and networks. Finally, 'storage controller' is any device with the intelligence to talk to a server and handle its read and write requests.
Second, let's take a look at all the different flavors of storage virtualization that IBM has developed over the past 30 years.
IBM introduces the S/370 with the OS/VS1 operating system. "VS" here refers to virtual storage, and in this case internal server memory was swapped out to physical disk. Using a table mapping, disk was made to look like an extension of main memory.
IBM introduces the IBM 3850 Mass Storage System (MSS). Until this time, programs that ran on mainframes had to be acutely aware of the device types being written, as each device type had different block, track and cylinder sizes, so a program written for one device type would have to be modified to work with a different device type. The MSS was able to take four 3350 disks, and a lot of tapes, and make them look like older 3330 disks, since most programs were still written for the 3330 format. The MSS was a way to deliver new 3350 disk to a 3330-oriented ecosystem, and greatly reduce the cost by handling tape on the back end. The table mapping was one virtual 3330 disk (100 MB) to two physical tapes (50 MB each). Back then, all of the mainframe disk systems had separate controllers. The 3850 used a 3831 controller that talked to the servers.
IBM invents Redundant Array of Independent Disk (RAID) technology. The table mapping is one or more virtual "Logical Units" (or "LUNs") to two or more physical disks. Data is striped, mirrored and paritied across the physical drives, making the LUNs look and feel like disks, but with faster performance and higher reliability than the physical drives they were mapped to. RAID could be implemented in the server as software, on top or embedded into the operating system, in the host bus adapter, or on the controller itself. The vendor that provided the RAID software or HBA did not have to be the same as the vendor that provided the disk, so in a sense, this avoided "vendor lock-in".Today, RAID is almost always done in the external storage controller.
IBM introduces the Personal Computer. One of the features of DOS is the ability to make a "RAM drive". This is technology that runs in the operating system to make internal memory look and feel like an external drive letter. Applications that already knew how to read and write to drive letters could work unmodified with these new RAM drives. This had the advantage that the files would be erased when the system was turned off, so it was perfect for temporary files. Of course, other operating systems today have this feature, UNIX has a /tmp directory in memory, and z/OS uses VIO storage pools.
This is important, as memory would be made to look like disk externally, as "cache", in the 1990s.
IBM AIX v3 introduces Logical Volume Manager (LVM). LVM maps the LUNs from external RAID controllers into virtual disks inside the UNIX server. The mapping can combine the capacity of multiple physical LUNs into a large internal volume. This was all done by software within the server, completely independent of the storage vendor, so again no lock-in.
IBM introduces the Virtual Tape Server (VTS). This was a disk array that emulated a tape library. A mapping of virtual tapes to physical tapes was done to allow full utilization of larger and larger tape cartridges. While many people today mistakenly equate "storage virtualization" with "disk virtualization", in reality it can be implemented on other forms of storage. The disk array was referred to as the "Tape Volume Cache". By using disk, the VTS could mount an empty "scratch" tape instantaneously, since no physical tape had to be mounted for this purpose.
Contradicting its "tape is dead" mantra, EMC later developed its CLARiiON disk library that emulates a virtual tape library (VTL).
IBM introduces the SAN Volume Controller. It involves mapping virtual disks to manage disks that could be from different frames from different vendors. Like other controllers, the SVC has multiple processors and cache memory, with the intelligence to talk to servers, and is similar in functionality to the controller components you might find inside monolithic "controller+disk" configurations like the IBM DS8300, EMC Symmetrix, or HDS TagmaStore USP. SVC can map the virtual disk to physical disk one-for-one in "image mode", as HDS does, or can also map virtual disks across physical managed disks, using a similar mapping table, to provide advantages like performance improvement through striping. You can take any virtual disk out of the SVC system simply by migrating it back to "image mode" and disconnecting the LUN from management. Again, no vendor lock-in.
The HDS USP and NSC can run as regular disk systems without virtualization, or the virtualization can be enabled to allow external disks from other vendors. HDS usually counts all USP and NSC sold, but never mention what percentage these have external disks attached in virtualization mode. Either they don't track this, or too embarrassed to publish the number. (My guess: single digit percentage).
Few people remember that IBM also introduced virtualization in both controller+disk and SAN switch form factors. The controller+disk version was called "SAN Integration Server", but people didn't like the "vendor lock-in" having to buy the internal disk from IBM. They preferred having it all external disk, with plenty of vendor choices. This is perhaps why Hitachi now offers a disk-less version of the NSC 55, in an attempt to be more like IBM's SVC.
IBM also had introduced the IBM SVC for Cisco 9000 blade. Our clients didn't want to upgrade their SAN switch networking gear just to get the benefits of disk virtualization. Perhaps this is the same reason EMC has done so poorly with its "Invista" offering.
So, bottom line, storage virtualization can, and has, been delivered in the operating system software, in the server's host bus adapter, inside SAN switches, and in storage controllers. It can be delivered anywhere in the path between application and physical media. Today, the two major vendors that provide disk virtualization "in the storage controller" are IBM and HDS, and the three major vendors that provide tape virtualization "in the storage controller" are IBM, Sun/STK, and EMC. All of these involve a mapping of logical to physical resources. Hitachi uses a one-for-one mapping, whereas IBM additionally offers more sophisticated mappings as well.
technorati tags: IBM, disk, tape, storage, virtualization, Hu Yoshia, HDS, Hitachi, TagmaStore, USP, NSC, disk-less, SAN Volume Controller, LVM, AIX, RAID, SAN, blade, Sun, STK, Cisco, EMC, Invista,
It's official! My "blook" Inside System Storage - Volume I
is now available.
|This blog-based book, or “blook”, comprises the first twelve months of posts from this Inside System Storage blog,165 posts in all, from September 1, 2006 to August 31, 2007. Foreword by Jennifer Jones. 404 pages.|
- IT storage and storage networking concepts
- IBM strategy, hardware, software and services
- Disk systems, Tape systems, and storage networking
- Storage and infrastructure management software
- Second Life, Facebook, and other Web 2.0 platforms
- IBM’s many alliances, partners and competitors
- How IT storage impacts society and industry
You can choose between hardcover (with dust jacket) or paperback versions:
This is not the first time I've been published. I have authored articles for storage industry magazines, written large sections of IBM publications and manuals, submitted presentations and whitepapers to conference proceedings, and even had a short story published with illustrations by the famous cartoon writer[Ted Rall].
But I can say this is my first blook, and as far as I can tell, the first blook from IBM's many bloggers on DeveloperWorks, and the first blook about the IT storage industry.I got the idea when I saw [Lulu Publishing] run a "blook" contest. The Lulu Blooker Prize is the world's first literary prize devoted to "blooks"--books based on blogs or other websites, including webcomics. The [Lulu Blooker Blog] lists past year winners. Lulu is one of the new innovative "print-on-demand" publishers. Rather than printing hundredsor thousands of books in advance, as other publishers require, Lulu doesn't print them until you order them.
I considered cute titles like A Year of Living Dangerously, orAn Engineer in Marketing La-La land, or Around the World in 165 Posts, but settled on a title that matched closely the name of the blog.
In addition to my blog posts, I provide additional insights and behind-the-scenes commentary. If you go to the Luluwebsite above, you can preview an entire chapter in its entirety before purchase. I have added a hefty 56-page Glossary of Acronyms and Terms (GOAT) with over 900 storage-related terms defined, which also doubles as an index back to the post (or posts) that use or further explain each term.
So who might be interested in this blook?
- Business Partners and Sales Reps looking to give a nice gift to their best clients and colleagues
- Managers looking to reward early-tenure employees and retain the best talent
- IT specialists and technicians wanting a marketing perspective of the storage industry
- Mentors interested in providing motivation and encouragement to their proteges
- Educators looking to provide books for their classroom or library collection
- Authors looking to write a blook themselves, to see how to format and structure a finished product
- Marketing personnel that want to better understand Web 2.0, Second Life and social networking
- Analysts and journalists looking to understand how storage impacts the IT industry, and society overall
- College graduates and others interested in a career as a storage administrator
And yes, according to Lulu, if you order soon, you can have it by December 25.
technorati tags: IBM, blook, Volume I, Jennifer Jones, system, storage, strategy, hardware, software, services, disk, tape, networking, SAN, secondlife, Web2.0, facebook, Lulu, publishing, Blooker Prize, articles, magazines, proceedings, Ted Rall, insights, glossary, early-tenure, mentors, library, classroom, administrator, print, publish, on demand
Well, this week I am in Maryland, just outside of Washington DC. It's a bit cold here.
Robin Harris over at StorageMojo put out this Open Letter to Seagate, Hitachi GST, EMC, HP, NetApp, IBM and Sun about the results of two academic papers, one from Google, and another from Carnegie Mellon University (CMU). The papers imply that the disk drive module (DDM) manufacturers have perhaps misrepresented their reliability estimates, and asks major vendors to respond. So far, NetAppand EMC have responded.
I will not bother to re-iterate or repeat what others have said already, but make just a few points. Robin, you are free to consider this "my" official response if you like to post it on your blog, or point to mine, whatever is easier for you. Given that IBM no longer manufacturers the DDMs we use inside our disk systems, there may not be any reason for a more formal response.
- Coke and Pepsi buy sugar, Nutrasweet and Splenda from the same sources
Somehow, this doesn't surprise anyone. Coke and Pepsi don't own their own sugar cane fields, and even their bottlers are separate companies. Their job is to assemble the components using super-secret recipes to make something that tastes good.
IBM, EMC and NetApp don't make DDMs that are mentioned in either academic study. Different IBM storage systems uses one or more of the following DDM suppliers:
- Seagate (including Maxstor they acquired)
- Hitachi Global Storage Technologies, HGST (former IBM division sold off to Hitachi)
In the past, corporations like IBM was very "vertically-integrated", making every component of every system delivered.IBM was the first to bring disk systems to market, and led the major enhancements that exist in nearly all disk drives manufactured today. Today, however, our value-add is to take standard components, and use our super-secret recipe to make something that provides unique value to the marketplace. Not surprisingly, EMC, HP, Sun and NetApp also don't make their own DDMs. Hitachi is perhaps the last major disk systems vendor that also has a DDM manufacturing division.
So, my point is that disk systems are the next layer up. Everyone knows that individual components fail. Unlike CPUs or Memory, disks actually have moving parts, so you would expect them to fail more often compared to just "chips".
If you don't feel the MTBF or AFR estimates posted by these suppliers are valid, go after them, not the disk systems vendors that use their supplies. While IBM does qualify DDM suppliers for each purpose, we are basically purchasing them from the same major vendors as all of our competitors. I suspect you won't get much more than the responses you posted from Seagate and HGST.
- American car owners replace their cars every 59 months
According to a frequently cited auto market research firm, the average time before the original owner transfers their vehicle -- purchased or leased -- is currently 59 months.Both studies mention that customers have a different "definition" of failure than manufacturers, and often replace the drives before they are completely kaput. The same is true for cars. Americans give various reasons why they trade in their less-than-five-year cars for newer models. Disk technologies advance at a faster pace, so it makes sense to change drives for other business reasons, for speed and capacity improvements, lower power consumption, and so on.
The CMU study indicated that 43 percent of drives were replaced before they were completely dead.So, if General Motors estimated their cars lasted 9 years, and Toyota estimated 11 years, people still replace them sooner, for other reasons.
At IBM, we remind people that "data outlives the media". True for disk, and true for tape. Neither is "permanent storage", but rather a temporary resting point until the data is transferred to the next media. For this reason, IBM is focused on solutions and disk systems that plan for this inevitable migration process. IBM System Storage SAN Volume Controller is able to move active data from one disk system to another; IBM Tivoli Storage Manager is able to move backup copies from one tape to another; and IBM System Storage DR550 is able to move archive copies from disk and tape to newer disk and tape.
If you had only one car, then having that one and only vehicle die could be quite disrupting. However, companies that have fleet cars, like Hertz Car Rentals, don't wait for their cars to completely stop running either, they replace them well before that happens. For a large company with a large fleet of cars, regularly scheduled replacement is just part of doing business.
This brings us to the subject of RAID. No question that RAID 5 provides better reliability than having just a bunch of disks (JBOD). Certainly, three copies of data across separate disks, a variation of RAID 1, will provide even more protection, but for a price.
Robin mentions the "Auto-correlation" effect. Disk failures bunch up, so one recent failure might mean another DDM, somewhere in the environment, will probably fail soon also. For it to make a difference, it would (a) have to be a DDM in the same RAID 5 rank, and (b) have to occur during the time the first drive is being rebuilt to a spare volume.
- The human body replaces skin cells every day
So there are individual DDMs, manufactured by the suppliers above; disk systems, manufactured by IBM and others, and then your entire IT infrastructure. Beyond the disk system, you probably have redundant fabrics, clustered servers and multiple data paths, because eventually hardware fails.
People might realize that the human body replaces skin cells every day. Other cells are replaced frequently, within seven days, and others less frequently, taking a year or so to be replaced. I'm over 40 years old, but most of my cells are less than 9 years old. This is possible because information, data in the form of DNA, is moved from old cells to new cells, keeping the infrastructure (my body) alive.
Our clients should approach this in a more holistic view. You will replace disks in less than 3-5 years. While tape cartridges can retain their data for 20 years, most people change their tape drives every 7-9 years, and so tape data needs to be moved from old to new cartridges. Focus on your information, not individual DDMs.
What does this mean for DDM failures. When it happens, the disk system re-routes requests to a spare disk, rebuilding the data from RAID 5 parity, giving storage admins time to replace the failed unit. During the few hours this process takes place, you are either taking a backup, or crossing your fingers.Note: for RAID5 the time to rebuild is proportional to the number of disks in the rank, so smaller ranks can be rebuilt faster than larger ranks. To make matters worse, the slower RPM speeds and higher capacities of ATA disks means that the rebuild process could take longer than smaller capacity, higher speed FC/SCSI disk.
According to the Google study, a large portion of the DDM replacements had no SMART errors to warn that it was going to happen. To protect your infrastructure, you need to make sure you have current backups of all your data. IBM TotalStorage Productivity Center can help identify all the data that is "at risk", those files that have no backup, no copy, and no current backup since the file was most recently changed. A well-run shop keeps their "at risk" files below 3 percent.
So, where does that leave us?
- ATA drives are probably as reliable as FC/SCSI disk. Customers should chose which to use based on performance and workload characteristics. FC/SCSI drives are more expensive because they are designed to run at faster speeds, required by some enterprises for some workloads. IBM offers both, and has tools to help estimate which products are the best match to your requirements.
- RAID 5 is just one of the many choices of trade-offs between cost and protection of data. For some data, JBOD might be enough. For other data that is more mission critical, you might choose keeping two or three copies. Data protection is more than just using RAID, you need to also consider point-in-time copies, synchronous or asynchronous disk mirroring, continuous data protection (CDP), and backup to tape media. IBM can help show you how.
- Disk systems, and IT environments in general, are higher-level concepts to transcend the failures of individual components. DDM components will fail. Cache memory will fail. CPUs will fail. Choose a disk systems vendor that combines technologies in unique and innovative ways that take these possibilities into account, designed for no single point of failure, and no single point of repair.
So, Robin, from IBM's perspective, our hands are clean. Thank you for bringing this to our attention and for giving me the opportunity to highlight IBM's superiority at the systems level.
technorati tags: IBM, Seagate, Hitachi, HGST, EMC, NetApp, HP, HDS, Sun, Google, CMU, DDM, Fujitsu, MTBF, MTTF, AFR, ARR, JBOD, RAID, Tivoli, SVC, DR550, CDP, FC, SCSI, disk, tape, SAN,
Well, we had another successful event in Second Life today.
Unlike our April 26 launch of our System Storage products for IBM Business Partners only, this time we decided this time to make it as a "Meet the Storage Experts" Q&A Panel format, and open up registration to everyone. Thesubject matter experts sat at the front of the room on four stools. We had six rows of chairs arrangedsemi-circularly.
Shown above, from left to right, are the avatars of our four experts:
- Steve Grillo
- IBM System Storage N series, focusing on recent N3000 disk system announcements
- Harold Pike (holding the microphone while speaking)
- IBM System Storage DS3000 and DS4000 series, focusing on recent DS3000 disk system announcements
- Eric Buckley
- IBM System Storage TS series, focusing on recent TS2230, TS3400 and TS7700 tape system announcements
- Pete Danforth
- IBM storage networking, focusing on recent IBM SAN256B director blade announcements
(you can read more about these products here:July announcements
While Eric was a veteran Second Lifer, having presented at our April event, the other three were trainedon how to raise their hand, speak into the microphone, sit on the stool, and so on. I want to thank allof our experts for putting in this effort!
The event was produced by Katrina H Smith. She did a great job, and made sure we were on top ofall the issues and tasks required to get the job done. Running a Second Life event is every bit ashard as running a real face-to-face event. We had several meetings to discuss venue details, placementof chairs, placement of product demos, audio/video recording, wall decorations, tee-shirt and coffee mug design, logistics, and so on.
I acted as moderator/emcee for the event. That is my back in the picture above. The process wassimple, modeled after the "Birds of a Feather" sessions at events like SHARE and the IBMStorage and Storage Networking Symposium. We threw out a list of topics the experts would cover,and people in the audience would "raise their left hand". I, as the moderator, would then walkover to each person, and hold out the microphone for them to ask the question. I would then repeat the question and ask the appropriate expert to provide an answer. We defined gestures onhow to "raise hand" and "put hand down" that we gave to each registered participant.
We had four dedicated "camera-avatars" in world to capture both video and screenshots.Our video editors are now working to edit "highlight videos" that we can use at future events, for training materials, and for our internal "BlueTube" online video system.
The room was filled with examples of each of our products, made into 3D objects that were dimensionallycorrect, and "textured" with photographs of the actual products. If you click on an object, you get a "notecard" that provided more information. Special thanks to Scott Bissmeyer for making all of theseobjects for us.
We made posters of each expert and placed them in all four corners of the room. On the bottom of each coffee mug was a picture of each of the experts, and if you walked under each of the posters, you were"dispensed" a coffee mug matching the expert shown in the poster.Participants could "Collect all Four!" When you bring the coffee mug up to takea sip, the picture on the bottom of the mug is exposed for all to see.And as a final give-away to the audience, we made a variety of event tee-shirts and polo-shirts.
At the end of the session, we asked everyone to click on the "Survey" kiosk near the exit door. We askedsix simple questions using SurveyMonkey.com that took only a fewminutes to process. We found asking questions immediately at the end of the event was the best way tocapture this feedback.
From a "Green" perspective, we had people registered from the following countries: US, India, Mexico,Australia, United Kingdom, Brazil, Germany, Argentina, Chile, China, Canada, and Venezuela. Second Lifeallows all these people who probably could not travel, or could not afford the time and expense to travel,to participate in a simulated face-to-face meeting without energy consumption of traditional travel methods.
More importantly, we got several leads for business. People often ask "Yes, but is there any businessassociated with this?" This time, there was, based on the answers to the questions, several avatars asked for a real sales call to follow-up on the products and offerings they were discussed.
With such a great success, we have already scheduled our next Second Life event, November 8. Mark your calendars! I'll postmore details on the registration process of the November event when available.
technorati tags: IBM, secondlife, meet, the, storage, experts, Steve Grillo, Harold Pike, Eric Buckley, Pete Danforth, Katrina Smith, Scott Bissmeyer, US, India, Mexico, Australia, UK, Brazil, Germany, Argentina, Chile, China, Canada, Venezuela, Green, business
The proof-of-concept that IBM Haifa research center developed back in 1998 became what we now call the iSCSI protocol.The book iSCSI: The Universal Storage Connection
introduces the history as follows:
In the fall of 1999 IBM and Cisco met to discuss the possibility of combining their SCSI-over-TCP/IP efforts. After Cisco saw IBM's demonstration of SCSI over TCP/IP, the two companies agreed to develop a proposal that would be taken to the IETF for standardization.
There are three ways to introduce iSCSI into your data center:
- Through a gateway, like the IBM System Storage N series gateway, that allows iSCSI-based servers connect to FC-based storage devices
- Through a SAN switch or director, a FC-based server can access iSCSI-based storage, an iSCSI-based server accessing FC-based storage, or even iSCSI-based servers attaching to iSCSI-based storage.
- Directly through the storage controller.
IBM has been delivering the first method with its successful IBM System Storage N series gateway products, buttoday we have announced additional support for the second and third methods.Here's a quick recap.
- New SAN director blades
Supporting the second method, IBM TotalStorage SAN256B Director is enhanced to deliver iSCSI functionality with a new M48 iSCSI Blade, which includes 16 ports (8 Fibre Channel ports; and 8 Ethernet ports for iSCSI connectivity). We also announced a new Fibre Channel M48 Blade which provides 10 Gbps Fibre Channel Inter Switch Link (ISL) connectivity between SAN256B Directors.
- Entry Level Disk Systems
Supporting the third method, IBM introduces new iSCSI-capabable disk systems, including the IBM System Storage DS3300 model using SAS drives, N3300 A10/A20 models and N3600 A10/A20 models supporting use of FC and SATA drives.The DS3000 Express models include frequently requested options, including appropriate host bus adapters (HBA) and cables. Likewise, we have announced hardware features for our IBM N series , such as TCP offload engine (TOE) network interface cards (NIC), HBA and cables.
With support for Boot-over-iSCSI, diskless rack-optimized and blade servers can boot Windows or Linux over Ethernet,eliminating the management hassles with internal disk.
All of this is part of IBM's overall push into the Small and Medium size Business marketplace, making it easier to shop for and buy from IBM and its many IBM Business Partners, easier to deploy and install storage, and easier tomanage the storage once you have it.
technorati tags: IBM, Cisco, iSCSI, gateways, announcement, DS3300, N3300, N3600, A10, A20, SAS, FC, SATA, HBA, TOE, NIC, cables, SCSI, TCP, boot-over-iSCSI, SMB, Ethernet