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 )
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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.
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.
In case you haven't noticed, IBM System Storage makes most of their announcements on Tuesdays. IBM announced a lot today, so here is a quick run-down.
Cisco storage networking products
IBM continues to resell Cisco switches and directors, but now can offer these with a 1-year IBM warranty.
The entry-level Cisco 9124offers 8 to 24 ports. For IBM BladeCenter, IBM now offers the Cisco10-port and 20-port modules that slide into the back of the chassis, and are functionally equivalent to the 9124.The original BladeCenter came with a 16-port module with 14 internal, but only 2 external, which severely hamperedbandwidth connectivity to external storage. These new modules provide more external ports to relieve that constraint.
The midrange Cisco9200switches have two models, both with 16 fixed ports, with the option for a blade that can provide 12, 24 or 48 additional ports. The 9216A has 16 FCP ports, and the 9216i has 14 FCP ports, and 2 GbE ports to act as a router, such as toconnect to a remote location for business continuity using Metro Mirror or Global Mirror.
The enterprise-class Cisco 9500directors can support up to 528 ports.
TS3400 Tape Library
The new TS3400library is a small entry-level size library, supporting the enterprise-class TS1120 drive, providing interoperabilitywith the larger tape libraries, with all the support for tape encryption.
In addition to Linux, Unix, and WIndows, the TS1120 can now be connected to System i servers. In the past, the only IBMtape available to System i were the LTO models. There are a lot of businesses that need to comply with government regulations that are looking for tape encryption, and now IBM has made it accessible to more clients.
300GB drives at 15K RPM
The DS8000 can now support new drives with 300GB capacity at 15,000 RPM (15K). These can be up to 30 percent faster than the 10,000 RPM drives for typical workloads.
IBM continues its market leadership with these new set of features and offerings!
I would fall into the "not for me" category, at least at this time. The iPhone is GSM-capable phone with the ability to store 4GB or 8GB of music, photos and video, and has incorporated a 2 megapixel camera. Currently, I have separate components:
A cell phone that is GSM plus CDMA, with features like "speakerphone" which I use quite a lot, but NO camera.
A 7 megapixel camera, also very small, with removable memory cards.
A 60GB iPod, with music and photos. My model is older and doesn't handle videos.
Since I visit government agencies, research and development labs, and other places that don't allow cameras, I have to either chose a cell phone that does not have camera capability in it, or have a camera phone that I leave behind in the car or at the front desk. I have chosen to get cell phones with NO camera. So, NOT having a camera is a primary feature I look for, but this is getting harder and harder these days. I don't know if Apple plans to have a non-camera version of their iPhone, but that would be a deal-breaker for me.
I do carry a separate camera, and where it is permissible, use it separately. This is especially useful if you do a lot of whiteboard or flipchart presentations, and want to capture what you have written for later. (For a great example of how effectively whiteboards can be used, check out these videos from UPS.)A picture is worth a thousand words, and is easier to convey an idea with pictures, especially in countries that may not speak English. Last month, I got a 7 megapixel camera to replace my 5 megapixel. For my work, 2 megapixel as found in the iPhone is not detailed enough.
As for my iPod, I enjoy that I can carry 60GB of music and photos. When I go on vacations, I can bring my camera and iPod, and connect the two, transferring and viewing the pictures that I take. I can easily free up 5-10 GB of space on my iPod for photos in preparation for a trip, then replace that with music when I am back at home. I also use my iPod as a remote disk drive for my laptop on business trips. Again, the 4GB and 8GB may not be enough for what I need.
Printers were never converged into Personal Computers, but they did have their own convergence. I have a multi-function printer/scanner/fax machine. I used to have separate printer, scanner and fax machines, but now the technology is so inexpensive that it got all combined into one solution.
The same is happening for Storage Area Networking gear.
Thanks to Fibre Channel, switches and directors can handle both SCSI commands (FCP) and CCW commands (FICON). This allows the mainframe and distrbuted systems to converge their traffic onto a single network, and is less expensive than trying to maintain one network for the mainframes, and another for the distributed platforms.
On the SCSI side, there are now switches that let you have pluggable ports of different flavors. For example, you can have some ports be Fibre Channel to receive FCP, and other ports to be Ethernet to carry iSCSI. iSCSI is a protocol co-developed between IBM and Cisco to carry SCSI commands over Ethernet. Since most computers already have Ethernet "network interface cards" and most buildings are already wired with an Ethernet infrastructure, this provides a less expensive alternative to Fibre Channel.
Routers, and combination Router/Switches, can send all the FCP/FICON/iSCSI traffic over various long distances to remote data centers, using either iFCP or FCIP protocols. This is a less expensive alternative to dropping your own private "dark fiber" between the two locations, which often involves negotiating access rights to dig trenches through other people's property.
Which brings me back to Apple's iPhone. One device can make calls, watch video, and download webpages all because the networks have converged into sending all data in "packets". The network just routes packets from one place to another. It doesn't care that a packet is a voice packet, a video packet or a webpage packet. It doesn't matter.
"Users can pay for groceries and other purchases by swiping a phone over a reader that electronically communicates with a microchip on the phone. Phone owners confirm the purchase with the push of a button and the deal is complete.
The platform is the result of many years of trials around the world and will enable mobile contactless payments, remote payments, person-to-person payments, and mobile coupons."
Continuing on my theme of storage area networking, today I thought I would coverstorage networking at home.
Before the PC, corporate end-users had dumb terminals (displays) connected to mainframes (servers) thatwere then connected to external disk and tape (storage devices). This was all done with direct cable connections,then later through networks. The PC solved this by putting the display, server and storage into one unit, makingit more accessible to smaller businesses and individuals.
Many years ago, Microsoft started out with the vision "A PC on every desktop".The primary reason we even have networks is while everyone might have had their own PC, not everyone had their own printer. (Printers used to be part of IBM's storage division, which we explained as "storage on PAPER"!)Maybe if Microsoft's vision was "A PC and printer on every desktop", history might have turned up different.
Disclaimer: IBM has close business relationships with both Apple and Microsoft and others,providing the chips inside some of their products. I discuss them here not only becauseI am trying to get you to buy their products, and let IBM benefit indirectly from their success, but because they are newsworthy, and relevant to the topic at hand.
The "Apple TV" is not a TV at all, but rather a server, one that lets your television (your dumb terminal)access the video, audio and photos stored on your Mac or iPod (the storage device), all through a home network.(Sound familiar?)
Bill Gates from Microsoft gave the keynote, and this is probably his last appearance, as he is retiring in 2008,as we are reminded by thisfunny video, to move on to bigger, and better things. It is perhaps fitting that his retirement aligns with the end of the era for the PC.
Microsoft unveiled their Microsoft Windows Home Server, again a server that connects your television (dumb terminal) with your PC or Zune (storage device)all through your home network. (Sound familiar, again?)
Whereas Apple above pretty much shunned the gaming community, Microsoft embraced it with their internet-enabled Xbox360.Microsoft sold 10.4 million of these last year, which was 400 million more than they projected.
Our SAN technology partner Cisco wants to get in on this "home networking craze", as written about inInfoWorld andCnet.
My take on all this...the consumer electronics industry is taking clues from IBM's mainframe business. Not the first time this has happened, and probably not the last.
I already access photos and audio with my Tivo, from both my Mac AND my PC,so not much new here for me. Getting my home network connected was one of mytech highlights of 2006 and organizing my audio content was done withILM for my iPod.
Bypassing the PC, by being able to have your television, handheld or phone access data directly will greatlyincrease the demand for storage from businesses that provide information and content, and for storage networking technology in the home. It will be interesting how this all plays out in 2007.