Has EMC stooped so low that they have to resort to Hitachi math for their latest performance claims?
Readers might remember that just a few months ago, I had a blog post [Is this what HDS tells our mainframe clients?] pointing out the outlandish comparison Hitachi was using in their presentations. Their response was to cover it up, forcing me to follow up with my post [The Cover-up is worse than the original crime]. To their credit, they eventually removed the false and misleading information from their materials.
Now an avid reader of my blog has brought this to my attention. Apparently,
EMC has been showing customers a presentation
[Accelerating Storage Transformation with VMAX and VPLEX] with false and misleading comparison claims between IBM DS8000, HDS VSP and EMC VMAX 40K disk system performance.
(FTC Disclosure: This would be a good time to remind my readers that I work for IBM and own IBM stock. I do not endorse any of the EMC or HDS products mentioned in this post, and have no financial affiliation or investments directly with either EMC nor HDS. I am basing my information solely on the presentation posted on the internet and other sources publicly available, and not on any misrepresentations from EMC speakers at the various conferences where these charts might have been shown.)
The problem with misinformation is that it is not always obvious. The EMC presentation is quite pretty and professional-looking. It is the typical slick, attention-getting, low-content, over-simplified marketing puffery you have come to expect from EMC. There are two slides in particular that I have issue with.
This first graphic implies that IBM and HDS are nearly tied in performance, but that EMC VMAX 40K has nearly triple that bandwidth. Overall the slide has very little detail. That makes it difficult to determine what exactly is being claimed and whether a fair comparison is being made.
- The title claims that VMAX 40K is "#1 in High Bandwidth Apps". Only three disk systems are shown so the claim appears to be relative to only the three systems. The wording "High Bandwidth Apps" is confusing considering the cited numbers are for disk systems and no application is identified. By comparison, IBM SONAS can drive up to 105 GB/sec sequential bandwidth, nearly double what EMC claims for its VMAX 40K, so EMC is certainly not even close to #1.
- Is the workload random or sequential? That is not easy to determine. The use of "GB/s" along with the large block size of 128KB implies the I/O workload is sequential, which is great for some workloads like high performance computing, technical computing and video broadcasts. Random workloads, on the other hand, are usually measured in I/Os per second (IOPS) with a block size ranging 4KB to 64KB. (I am assuming the 128K blocks refers to 128KB block size, and not reading the same block of cache 128,000 times.)
- The slide states "Maximum Sustainable RRH Bandwidth 128K Blocks". The acronym "RRH" is not defined; but I suspect this refers to "random read hits". For random workloads, 100 percent random read hits from cache represents one corner of the infamous "four corners" test. Real-world workloads have a mix of reads and writes, and a mix of cache hits and cache misses. It is also unclear whether the hits are from standard data cache or from internal buffers in adapters (perhaps accessing the same blocks repeatedly) or something else. So is this really for a random workload, or a sequential workload?
(The term "Hitachi Math" was coined by an EMC blogger precisely to slam Hitachi Data Systems for their blatant use of four-corners results, claiming that spouting ridiculously large, but equally unrealistic, 100 percent random read hit results don't provide any useful information. I agree. There are much better industry-standard benchmarks available, such as SPC-1 for random workloads, SPC-2 for sequential workloads, and even benchmarks for specific applications, that represent real-world IT environments. To shame HDS for their use of four-corners results, only for EMC themselves to use similar figures in their own presentation is truly hypocritical of them!)
- The IBM system is identified as "DS8000". DS8000 is a generic family name that applies to multiple generations of systems first introduced in 2004. The specific model is not identified, but that is critical information. Is this a first generation DS8100, or the latest DS8800, or something in between?
The slide says "Full System Configs", but that is not defined and configuration details are not identified. Configuration details, also critical information in assessing system performance capabilities, are not specified. If the EMC box costs seven times more than IBM or HDS, would you really buy it to get 3x more performance? Is the EMC packed with the maximum amount of SSD? Were there any SSD in the IBM or HDS boxes to match?
The source of the claimed IBM DS8000 performance numbers is not identified. Did they run their own tests? While I cannot tell, the VMAX may have been configured with 64 Fibre Channel 8Gbps host connections. In that case each channel is theoretically capable of supporting about 800 MB/s at 100% channel utilization. Multiplying 64 x 800MB/s = 51.2GB/s, so did EMC just do the performance comparison on the back of a napkin, assuming there are no other bottlenecks in the system? Even then, I would not round up 51.2 to 52!
- Response times were not identified. For random I/Os, response time is a very important metric. It is possible that the Symmetrix was operating with some resources at 100% utilization to get the highest GB/s result, but that would likely make I/O response times unacceptable for real-world random I/O workloads.
IBM and HDS have both published Storage Performance Council [SPC] industry-standard performance benchmarks. EMC has not published any SPC benchmarks for VMAX systems. If EMC is interested in providing customers with audited, detailed performance information along with detailed configuration information, all based on benchmarks designed to represent real-world workloads, EMC can always publish SPC benchmark results as IBM and other vendors have done. In past blog fights, EMC resorts to the excuse that SPC isn't perfect, but can they really argue that vague and unrealistic claims cited in its presentation are better?
The second graphic is so absurd, you would think it came directly from Larry Ellison at an Oracle OpenWorld keynote session. EMC is comparing a configuration with VMAX 40K plus an EMC VFCache host-side flash memory cache card to a configuration with an IBM and HDS disk system without host-side flash memory cache also configured. The comparison is clearly apples-to-oranges. Other disk system configuration details are also omitted.
FAST VP is EMC's name for its sub-volume drive tiering feature, comparable to IBM Easy Tier and Hitachi's Dynamic Tiering. The graph implies that IBM and HDS can only achieve a modest increment improvement from their sub-volume tiering. I beg to differ. I have seen various cases where a small amount of SSD on IBM DS8000 series can drastically improve performance 200 to 400 percent.
The "DBClassify" shown on the graph is a tool run as part of an EMC professional services offering called Database Performance Tiering Assessment, makes recommendations for storing various database objects on different drive tiers based on object usage and importance. Do you really need to pay for professional services? With IBM Easy Tier, you just turn it on, and it works. No analysis required, no tools, no professional services, and no additional charge!
- VFCache is an optional product from EMC that currently has no integration whatsoever with VMAX. A fair comparison would have included a host-side flash memory cache (from any vendor) when the IBM or HDS storage system was configured. Or leave it out altogether and just focus on the sub-volume tiering comparison.
Keep in mind that EMC's VFCache supports only selected x86-based hosts. IBM has published a [Statement of Direction] indicating that it will also offer this for Power systems running AIX and Linux host-side flash memory cache integrated with DS8000 Easy Tier.
I feel EMC's claims about IBM DS8000 performance are vague and misleading. EMC appears to lack the kind of technical marketing integrity that IBM strives to attain.
Since EMC is not able or willing to publish fair and meaningful performance comparisons, it is up to me to set the record straight and point out EMC's failings in this matter.
Reminder: It's not to late to register for my Webcast "Solving the Storage Capacity Crisis" on Tuesday, September 25. See my blog post [Upcoming events in September] to register!
technorati tags: IBM, DS8000, DS8800, HDS, VSP, EMC, VMAX, Symmetrix, VFCache, Easy Tier, FAST VP
A long time ago, perhaps in the early 1990s, I was an architect on the component known today as DFSMShsm on z/OS mainframe operationg system. One of my job responsibilities was to attend the biannual [SHARE conference to listen to the requirements of the attendees on what they would like added or changed to the DFSMS, and ask enough questions so that I can accurately present the reasoning to the rest of the architects and software designers on my team. One person requested that the DFSMShsm RELEASE HARDCOPY should release "all" the hardcopy. This command sends all the activity logs to the designated SYSOUT printer. I asked what he meant by "all", and the entire audience of 120 some attendees nearly fell on the floor laughing. He complained that some clever programmer wrote code to test if the activity log contained only "Starting" and "Ending" message, but no error messages, and skip those from being sent to SYSOUT. I explained that this was done to save paper, good for the environment, and so on. Again, howls of laughter. Most customers reroute the SYSOUT from DFSMS from a physical printer to a logical one that saves the logs as data sets, with date and time stamps, so having any "skipped" leaves gaps in the sequence. The client wanted a complete set of data sets for his records. Fair enough.
When I returned to Tucson, I presented the list of requests, and the immediate reaction when I presented the one above was, "What did he mean by ALL? Doesn't it release ALL of the logs already?" I then had to recap our entire dialogue, and then it all made sense to the rest of the team. At the following SHARE conference six months later, I was presented with my own official "All" tee-shirt that listed, and I am not kidding, some 33 definitions for the word "all", in small font covering the front of the shirt.
I am reminded of this story because of the challenges explaining complicated IT concepts using the English language which is so full of overloaded words that have multiple meanings. Take for example the word "protect". What does it mean when a client asks for a solution or system to "protect my data" or "protect my information". Let's take a look at three different meanings:
- Unethical Tampering
The first meaning is to protect the integrity of the data from within, especially from executives or accountants that might want to "fudge the numbers" to make quarterly results look better than they are, or to "change the terms of the contract" after agreements have been signed. Clients need to make sure that the people authorized to read/write data can be trusted to do so, and to store data in Non-Erasable, Non-Rewriteable (NENR) protected storage for added confidence. NENR storage includes Write-Once, Read-Many (WORM) tape and optical media, disk and disk-and-tape blended solutions such as the IBM Grid Medical Archive Solution (GMAS) and IBM Information Archive integrated system.
- Unauthorized Access
The second meaning is to protect access from without, especially hackers or other criminals that might want to gather personally-identifiably information (PII) such as social security numbers, health records, or credit card numbers and use these for identity theft. This is why it is so important to encrypt your data. As I mentioned in my post [Eliminating Technology Trade-Offs], IBM supports hardware-based encryption FDE drives in its IBM System Storage DS8000 and DS5000 series. These FDE drives have an AES-128 bit encryption built-in to perform the encryption in real-time. Neither HDS or EMC support these drives (yet). Fellow blogger Hu Yoshida (HDS) indicates that their USP-V has implemented data-at-rest in their array differently, using backend directors instead. I am told EMC relies on the consumption of CPU-cycles on the host servers to perform software-based encryption, either as MIPS consumed on the mainframe, or using their Powerpath multi-pathing driver on distributed systems.
There is also concern about internal employees have the right "need-to-know" of various research projects or upcoming acquisitions. On SANs, this is normally handled with zoning, and on NAS with appropriate group/owner bits and access control lists. That's fine for LUNs and files, but what about databases? IBM's DB2 offers Label-Based Access Control [LBAC] that provides a finer level of granularity, down to the row or column level. For example, if a hospital database contained patient information, the doctors and nurses would not see the columns containing credit card details, the accountants would not see the columnts containing healthcare details, and the individual patients, if they had any access at all, would only be able to access the rows related to their own records, and possibly the records of their children or other family members.
- Unexpected Loss
The third meaning is to protect against the unexpected. There are lots of ways to lose data: physical failure, theft or even incorrect application logic. Whatever the way, you can protect against this by having multiple copies of the data. You can either have multiple copies of the data in its entirety, or use RAID or similar encoding scheme to store parts of the data in multiple separate locations. For example, with RAID-5 rank containing 6+P+S configuration, you would have six parts of data and one part parity code scattered across seven drives. If you lost one of the disk drives, the data can be rebuilt from the remaining portions and written to the spare disk set aside for this purpose.
But what if the drive is stolen? Someone can walk up to a disk system, snap out the hot-swappable drive, and walk off with it. Since it contains only part of the data, the thief would not have the entire copy of the data, so no reason to encrypt it, right? Wrong! Even with part of the data, people can get enough information to cause your company or customers harm, lose business, or otherwise get you in hot water. Encryption of the data at rest can help protect against unauthorized access to the data, even in the case when the data is scattered in this manner across multiple drives.
To protect against site-wide loss, such as from a natural disaster, fire, flood, earthquake and so on, you might consider having data replicated to remote locations. For example, IBM's DS8000 offers two-site and three-site mirroring. Two-site options include Metro Mirror (synchronous) and Global Mirror (asynchronous). The three-site is cascaded Metro/Global Mirror with the second site nearby (within 300km) and the third site far away. For example, you can have two copies of your data at site 1, a third copy at nearby site 2, and two more copies at site 3. Five copies of data in three locations. IBM DS8000 can send this data over from one box to another with only a single round trip (sending the data out, and getting an acknowledgment back). By comparison, EMC SRDF/S (synchronous) takes one or two trips depending on blocksize, for example blocks larger than 32KB require two trips, and EMC SRDF/A (asynchronous) always takes two trips. This is important because for many companies, disk is cheap but long-distance bandwidth is quite expensive. Having five copies in three locations could be less expensive than four copies in four locations.
Fellow blogger BarryB (EMC Storage Anarchist) felt I was unfair pointing out that their EMC Atmos GeoProtect feature only protects against "unexpected loss" and does not eliminate the need for encryption or appropriate access control lists to protect against "unauthorized access" or "unethical tampering".
(It appears I stepped too far on to ChuckH's lawn, as his Rottweiler BarryB came out barking, both in the [comments on my own blog post], as well as his latest titled [IBM dumbs down IBM marketing (again)]. Before I get another rash of comments, I want to emphasize this is a metaphor only, and that I am not accusing BarryB of having any canine DNA running through his veins, nor that Chuck Hollis has a lawn.)
As far as I know, the EMC Atmos does not support FDE disks that do this encryption for you, so you might need to find another way to encrypt the data and set up the appropriate access control lists. I agree with BarryB that "erasure codes" have been around for a while and that there is nothing unsafe about using them in this manner. All forms of RAID-5, RAID-6 and even RAID-X on the IBM XIV storage system can be considered a form of such encoding as well. As for the amount of long-distance bandwidth that Atmos GeoProtect would consume to provide this protection against loss, you might question any cost savings from this space-efficient solution. As always, you should consider both space and bandwidth costs in your total cost of ownership calculations.
Of course, if saving money is your main concern, you should consider tape, which can be ten to twenty times cheaper than disk, affording you to keep a dozen or more copies, in as many time zones, at substantially lower cost. These can be encrypted and written to WORM media for even more thorough protection.
If these three methods of protection sound familiar, I mentioned them in my post about [Pulse conference, Data Protection Strategies] back in May 2008.
Did IBM XIV force EMC's hand to announce VMAXe? Let's take a stroll down memory lane.
In 2008, IBM XIV showed the world that it could ship a Tier-1, high-end, enterprise-class system using commodity parts. Technically, prior to its acquisition by IBM, the XIV team had boxes out in production since 2005. EMC incorrectly argued this announcement meant the death of the IBM DS8000. Just because EMC was unable to figure out how to have more than one high-end disk product, doesn't mean IBM or other storage vendors were equally challenged. Both IBM XIV and DS8000 are Tier-1, high-end, enterprise-class storage systems, as are the IBM N series N7900 and the IBM Scale-Out Network Attached Storage (SONAS).
In April 2009, EMC followed IBM's lead with their own V-Max system, based on Symmetrix Engenuity code, but on commodity x86 processors. Nobody at EMC suggested that the V-Max meant the death of their other Symmetrix box, the DMX-4, which means that EMC proved to themselves that a storage vendor could offer multiple high-end disk systems. Hitachi Data Systems (HDS) would later offer the VSP, which also includes some commodity hardware as well.
In July 2009, analysts at International Technology Group published their TCO findings that IBM XIV was 63 percent less expensive than EMC V-Max, in a whitepaper titled [COST/BENEFIT CASE
FOR IBM XIV STORAGE SYSTEM Comparing Costs for IBM XIV and EMC V-Max Systems]. Not surprisingly, EMC cried foul, feeling that EMC V-Max had not yet been successful in the field, it was too soon to compare newly minted EMC gear with a mature product like XIV that had been in production accounts for several years. Big companies like to wait for "Generation 1" of any new product to mature a bit before they purchase.
To compete against IBM XIV's very low TCO, EMC was forced to either deeply discount their Symmetrix, or counter-offer with lower-cost CLARiiON, their midrange disk offering. An ex-EMCer that now works for IBM on the XIV sales team put it in EMC terms -- "the IBM XIV provides a Symmetrix-like product at CLARiiON-like prices."
(Note: Somewhere in 2010, EMC dropped the hyphen, changing the name from V-Max to VMAX. I didn't see this formally announced anywhere, but it seems that the new spelling is the officially correct usage. A common marketing rule is that you should only rename failed products, so perhaps dropping the hyphen was EMC's way of preventing people from searching older reviews of the V-Max product.)
This month, IBM introduced the IBM XIV Gen3 model 114. The analysts at ITG updated their analysis, as there are now more customers that have either or both products, to provide a more thorough comparison. Their latest whitepaper, titled [Cost/Benefit Case for IBM XIV Systems: Comparing Cost
Structures for IBM XIV and EMC VMAX Systems], shows that IBM maintains its substantial cost savings advantage, representing 69 percent less Total Cost of Ownership (TCO) than EMC, on average, over the course of three years.
In response, EMC announced its new VMAXe, following the naming convention EMC established for VNX and VNXe. Customers cannot upgrade VNXe to VNX, nor VMAXe to VMAX, so at least EMC was consistent in that regard. Like the IBM XIV and XIV Gen3, the new EMC VMAXe eliminated "unnecessary distractions" like CKD volumes and FICON attachment needed for the IBM z/OS operating system on IBM System z mainframes. Fellow blogger Barry Burke from EMC explains everything about the VMAXe in his blog post [a big thing in a small package].
So, you have to wonder, did IBM XIV force EMC's hand into offering this new VMAXe storage unit? Surely, EMC sales reps will continue to lead with the more profitable DMX-4 or VMAX, and then only offer the VMAXe when the prospective customer mentions that the IBM XIV Gen3 is 69 percent less expensive. I haven't seen any list or street prices for the VMAXe yet, but I suspect it is less expensive than VMAX, on a dollar-per-GB basis, so that EMC will not have to discount it as much to compete against IBM.
technorati tags: IBM, XIV, Gen3, EMC, DMX-4, VMAX, V-Max, HDS, N7900, SONAS, DS8000, CKD, FICON, TCO
“In times of universal deceit, telling the truth will be a revolutionary act.”
-- George Orwell
Well, it has been over two years since I first covered IBM's acquisition of the XIV company. Amazingly, I still see a lot of misperceptions out in the blogosphere, especially those regarding double drive failures for the XIV storage system. Despite various attempts to [explain XIV resiliency] and to [dispel the rumors], there are still competitors making stuff up, putting fear, uncertainty and doubt into the minds of prospective XIV clients.
Clients love the IBM XIV storage system! In this economy, companies are not stupid. Before buying any enterprise-class disk system, they ask the tough questions, run evaluation tests, and all the other due diligence often referred to as "kicking the tires". Here is what some IBM clients have said about their XIV systems:
“3-5 minutes vs. 8-10 hours rebuild time...”
-- satisfied XIV client
“...we tested an entire module failure - all data is re-distributed in under 6 hours...only 3-5% performance degradation during rebuild...”
-- excited XIV client
“Not only did XIV meet our expectations, it greatly exceeded them...”
-- delighted XIV client
In this blog post, I hope to set the record straight. It is not my intent to embarrass anyone in particular, so instead will focus on a fact-based approach.
- Fact: IBM has sold THOUSANDS of XIV systems
XIV is "proven" technology with thousands of XIV systems in company data centers. And by systems, I mean full disk systems with 6 to 15 modules in a single rack, twelve drives per module. That equates to hundreds of thousands of disk drives in production TODAY, comparable to the number of disk drives studied by [Google], and [Carnegie Mellon University] that I discussed in my blog post [Fleet Cars and Skin Cells].
- Fact: To date, no customer has lost data as a result of a Double Drive Failure on XIV storage system
This has always been true, both when XIV was a stand-alone company and since the IBM acquisition two years ago. When examining the resilience of an array to any single or multiple component failures, it's important to understand the architecture and the design of the system and not assume all systems are alike. At it's core, XIV is a grid-based storage system. IBM XIV does not use traditional RAID-5 or RAID-10 method, but instead data is distributed across loosely connected data modules which act as independent building blocks. XIV divides each LUN into 1MB "chunks", and stores two copies of each chunk on separate drives in separate modules. We call this "RAID-X".
Spreading all the data across many drives is not unique to XIV. Many disk systems, including EMC CLARiiON-based V-Max, HP EVA, and Hitachi Data Systems (HDS) USP-V, allow customers to get XIV-like performance by spreading LUNs across multiple RAID ranks. This is known in the industry as "wide-striping". Some vendors use the terms "metavolumes" or "extent pools" to refer to their implementations of wide-striping. Clients have coined their own phrases, such as "stripes across stripes", "plaid stripes", or "RAID 500". It is highly unlikely that an XIV will experience a double drive failure that ultimately requires recovery of files or LUNs, and is substantially less vulnerable to data loss than an EVA, USP-V or V-Max configured in RAID-5. Fellow blogger Keith Stevenson (IBM) compared XIV's RAID-X design to other forms of RAID in his post [RAID in the 21st Centure].
- Fact: IBM XIV is designed to minimize the likelihood and impact of a double drive failure
The independent failure of two drives is a rare occurrence. More data has been lost from hash collisions on EMC Centera than from double drive failures on XIV, and hash collisions are also very rare. While the published worst-case time to re-protect from a 1TB drive failure for a fully-configured XIV is 30 minutes, field experience shows XIV regaining full redundancy on average in 12 minutes. That is 40 times less likely than a typical 8-10 hour window for a RAID-5 configuration.
A lot of bad things can happen in those 8-10 hours of traditional RAID rebuild. Performance can be seriously degraded. Other components may be affected, as they share cache, connected to the same backplane or bus, or co-dependent in some other manner. An engineer supporting the customer onsite during a RAID-5 rebuild might pull the wrong drive, thereby causing a double drive failure they were hoping to avoid. Having IBM XIV rebuild in only a few minutes addresses this "human factor".
In his post [XIV drive management], fellow blogger Jim Kelly (IBM) covers a variety of reasons why storage admins feel double drive failures are more than just random chance. XIV avoids load stress normally associated with traditional RAID rebuild by evenly spreading out the workload across all drives. This is known in the industry as "wear-leveling". When the first drive fails, the recovery is spread across the remaining 179 drives, so that each drive only processes about 1 percent of the data. The [Ultrastar A7K1000] 1TB SATA disk drives that IBM uses from HGST have specified 1.2 million hours mean-time-between-failures [MTBF] would average about one drive failing every nine months in a 180-drive XIV system. However, field experience shows that an XIV system will experience, on average, one drive failure per 13 months, comparable to what companies experience with more robust Fibre Channel drives. That's innovative XIV wear-leveling at work!
- Fact: In the highly unlikely event that a DDF were to occur, you will have full read/write access to nearly all of your data on the XIV, all but a few GB.
Even though it has NEVER happened in the field, some clients and prospects are curious what a double drive failure on an XIV would look like. First, a critical alert message would be sent to both the client and IBM, and a "union list" is generated, identifying all the chunks in common. The worst case on a 15-module XIV fully loaded with 79TB data is approximately 9000 chunks, or 9GB of data. The remaining 78.991 TB of unaffected data are fully accessible for read or write. Any I/O requests for the chunks in the "union list" will have no response yet, so there is no way for host applications to access outdated information or cause any corruption.
(One blogger compared losing data on the XIV to drilling a hole through the phone book. Mathematically, the drill bit would be only 1/16th of an inch, or 1.60 millimeters for you folks outside the USA. Enough to knock out perhaps one character from a name or phone number on each page. If you have ever seen an actor in the movies look up a phone number in a telephone booth then yank out a page from the phone book, the XIV equivalent would be cutting out 1/8th of a page from an 1100 page phone book. In both cases, all of the rest of the unaffected information is full accessible, and it is easy to identify which information is missing.)
If the second drive failed several minutes after the first drive, the process for full redundancy is already well under way. This means the union list is considerably shorter or completely empty, and substantially fewer chunks are impacted. Contrast this with RAID-5, where being 99 percent complete on the rebuild when the second drive fails is just as catastrophic as having both drives fail simultaneously.
- Fact: After a DDF event, the files on these few GB can be identified for recovery.
Once IBM receives notification of a critical event, an IBM engineer immediately connects to the XIV using remote service support method. There is no need to send someone physically onsite, the repair actions can be done remotely. The IBM engineer has tools from HGST to recover, in most cases, all of the data.
Any "union" chunk that the HGST tools are unable to recover will be set to "media error" mode. The IBM engineer can provide the client a list of the XIV LUNs and LBAs that are on the "media error" list. From this list, the client can determine which hosts these LUNs are attached to, and run file scan utility to the file systems that these LUNs represent. Files that get a media error during this scan will be listed as needing recovery. A chunk could contain several small files, or the chunk could be just part of a large file. To minimize time, the scans and recoveries can all be prioritized and performed in parallel across host systems zoned to these LUNs.
As with any file or volume recovery, keep in mind that these might be part of a larger consistency group, and that your recovery procedures should make sense for the applications involved. In any case, you are probably going to be up-and-running in less time with XIV than recovery from a RAID-5 double failure would take, and certainly nowhere near "beyond repair" that other vendors might have you believe.
- Fact: This does not mean you can eliminate all Disaster Recovery planning!
To put this in perspective, you are more likely to lose XIV data from an earthquake, hurricane, fire or flood than from a double drive failure. As with any unlikely disaster, it is best to have a disaster recovery plan than to hope it never happens. All disk systems that sit on a single datacenter floor are vulnerable to such disasters.
For mission-critical applications, IBM recommends using disk mirroring capability. IBM XIV storage system offers synchronous and asynchronous mirroring natively, both included at no additional charge.
For more about IBM XIV reliability, read this whitepaper [IBM XIV© Storage System: Reliability Reinvented]. To find out why so many clients LOVE their XIV, contact your local IBM storage sales rep or IBM Business Partner.
technorati tags: IBM, XIV, DDF, RAID-5, RAID-10, RAID-X, RAID-6, RAID-DP, HP, EVA, HDS, USP-V, EMC, CLARiiON, V-Max, Disaster Recovery, HGST, UltraStar, A7K1000
On my last blog post [Is this what HDS tells our mainframe clients?], I poked fun at Hu Yoshida's blog post that contained a graphic with questionable results. Suddenly, the blog post disappeared altogether. Poof! Gone!
Just so that I am not accused of taking a graph out of context, here is Hu's original post, in its entirety:
"Since my last post on Storage Performance Efficiency, Claus wrote on the use of HDP, Hitachi Dynamic Provisioning and HDT, Hitachi Dynamic Tiering for mainframes on Virtual Storage Platform (VSP). Naturally, this prompted me to think of the specific performance efficiency implications for mainframes.
HDP brings the performance benefits of automated wide striping and HDT automatically keeps the hot pages of data on the highest performance tier of storage for mainframes, just as it does for open systems. There are differences between open systems and mainframe implementation due to mainframe CKD and CCHHR formats for instance, the page size is optimized for mainframe storage formats and storage reclamation must be host initiate. For more information check out our website: http://www.hds.com/assets/pdf/how-to-apply-latest-advances-in-hitachi-mainframe-storage.pdf
There are also additional performance efficiencies specific for mainframes.
Mainframe HDP is the foundation for Extended Addressable Volumes, which increases the size of 3390 volumes from 65,520 cylinders to 262,668 cylinders. This, along with HyperPAV--which facilitates multiple accesses to a volume, addressing the problem of queuing on a very large volume with a single UCB--enhances throughput with many more concurrent I/O operations.
The thin provisioning of HDP also increases the performance of mainframe functions that move, copy, or replicate these thin volumes like Concurrent Copy, FlashCopy V02, and HUR, since the actual volumes are smaller.
If you have mainframes, check out the capacity and performance efficiency of VSP with HDP and HDT.
For other posts on maximizing storage and capacity efficiencies, check these out:
At this point, you might be wondering: "If Hu Yoshida deleted his blog post, how did Tony get a copy of it? Did Tony save a copy of the HTML source before Hu deleted it?" No. I should have, in retrospect, in case lawyers got involved. It turns out that deleting a blog post does not clear the various copies in various RSS Feed Reader caches. I was able to dig out the previous version from the vast Google repository. (Many thanks to my friends at Google!!!).
The graph itself was hosted separately has been deleted, but it was just taken from slide 10 of the HDS presentation [How to Apply the Latest Advances in Hitachi Mainframe Storage], so it was easy to recreate.
(Lesson to all bloggers: If you write a blog post, and later decide to remove it for whatever legal, ethical, moral reasons, it is better to edit the post to remove offending content, and add a comment that the post was edited, and why. Shrinking a 700-word article down to 'Sorry Folks - I decided to remove this blog post because...' would do the trick. This new edited version will then slowly propagate across to all of the RSS Feed Reader caches, eliminating most traces to the original. Of course, the original may have been saved by any number of your readers, but at least if you have an edited version, it can serve as the official or canonical version.)
Perhaps there was a reason why HDS did not want to make public the FUD its sales team use in private meetings with IBM mainframe clients. Whatever it was, this appears to be another case where the cover-up is worse than the original crime!
technorati tags: HDS, Hu Yoshida, VSP, EAV