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Tony Pearson is a Master Inventor and Senior IT Specialist for the IBM System Storage product line at the
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to IBM's developerWorks. In 2011, Tony celebrated his 25th year anniversary with IBM Storage on the same day as the IBM's Centennial. 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. You can also follow him on Twitter @az990tony.
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“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...”
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.
Here I am, day 11 of a 17-day business trip, on my last leg of the trip this week, in Kuala Lumpur in Malaysia. I have been flooded with requests to give my take on EMC's latest re-interpretation of storage virtualization, VPLEX.
I'll leave it to my fellow IBM master inventor Barry Whyte to cover the detailed technical side-by-side comparison. Instead, I will focus on the business side of things, using Simon Sinek's Why-How-What sequence. Here is a [TED video] from Garr Reynold's post
[The importance of starting from Why].
Let's start with the problem we are trying to solve.
Problem: migration from old gear to new gear, old technology to new technology, from one vendor to another vendor, is disruptive, time-consuming and painful.
Given that IT storage is typically replaced every 3-5 years, then pretty much every company with an internal IT department has this problem, the exception being those companies that don't last that long, and those that use public cloud solutions. IT storage can be expensive, so companies would like their new purchases to be fully utilized on day 1, and be completely empty on day 1500 when the lease expires. I have spoken to clients who have spent 6-9 months planning for the replacement or removal of a storage array.
A solution to make the data migration non-disruptive would benefit the clients (make it easier for their IT staff to keep their data center modern and current) as well as the vendors (reduce the obstacle of selling and deploying new features and functions). Storage virtualization can be employed to help solve this problem. I define virtualization as "technology that makes one set of resources look and feel like a different set of resources, preferably with more desirable characteristics.". By making different storage resources, old and new, look and feel like a single type of resource, migration can be performed without disrupting applications.
Before VPLEX, here is a breakdown of each solution:
Non-disruptive tech refresh, and a unified platform to provide management and functionality across heterogeneous storage.
Non-disruptive tech refresh, and a unified platform to provide management and functionality between internal tier-1 HDS storage, and external tier-2 heterogeneous storage.
Non-disruptive tech refresh, with unified multi-pathing driver that allows host attachment of heterogeneous storage.
New in-band storage virtualization device
Add in-band storage virtualization to existing storage array
New out-of-band storage virtualization device with new "smart" SAN switches
SAN Volume Controller
HDS USP-V and USP-VM
For IBM, the motivation was clear: Protect customers existing investment in older storage arrays and introduce new IBM storage with a solution that allows both to be managed with a single set of interfaces and provide a common set of functionality, improving capacity utilization and availability. IBM SAN Volume Controller eliminated vendor lock-in, providing clients choice in multi-pathing driver, and allowing any-to-any migration and copy services. For example, IBM SVC can be used to help migrate data from an old HDS USP-V to a new HDS USP-V.
With EMC, however, the motivation appeared to protect software revenues from their PowerPath multi-pathing driver, TimeFinder and SRDF copy services. Back in 2005, when EMC Invista was first announced, these three software represented 60 percent of EMC's bottom-line profit. (Ok, I made that last part up, but you get my point! EMC charges a lot for these.)
Back in 2006, fellow blogger Chuck Hollis (EMC) suggested that SVC was just a [bump in the wire] which could not possibly improve performance of existing disk arrays. IBM showed clients that putting cache(SVC) in front of other cache(back end devices) does indeed improve performance, in the same way that multi-core processors successfully use L1/L2/L3 cache. Now, EMC is claiming their cache-based VPLEX improves performance of back-end disk. My how EMC's story has changed!
So now, EMC announces VPLEX, which sports a blend of SVC-like and Invista-like characteristics. Based on blogs, tweets and publicly available materials I found on EMC's website, I have been able to determine the following comparison table. (Of course, VPLEX is not yet generally available, so what is eventually delivered may differ.)
Scalable, 1 to 4 node-pairs
One size fits all, single pair of CPCs
SVC-like, 1 to 4 director-pairs
Works with any SAN switches or directors
Required special "smart" switches (vendor lock-in)
SVC-like, works with any SAN switches or directors
Broad selection of IBM Subsystem Device Driver (SDD) offered at no additional charge, as well as OS-native drivers Windows MPIO, AIX MPIO, Solaris MPxIO, HP-UX PV-Links, VMware MPP, Linux DM-MP, and comercial third-party driver Symantec DMP.
Limited selection, with focus on priced PowerPath driver
Invista-like, PowerPath and Windows MPIO
Read cache, and choice of fast-write or write-through cache, offering the ability to improve performance.
No cache, Split-Path architecture cracked open Fibre Channel packets in flight, delayed every IO by 20 nanoseconds, and redirected modified packets to the appropriate physical device.
SVC-like, Read and write-through cache, offering the ability to improve performance.
Space-Efficient Point-in-Time copies
SVC FlashCopy supports up to 256 space-efficient targets, copies of copies, read-only or writeable, and incremental persistent pairs.
Like Invista, No
Remote distance mirror
Choice of SVC Metro Mirror (synchronous up to 300km) and Global Mirror (asynchronous), or use the functionality of the back-end storage arrays
No native support, use functionality of back-end storage arrays, or purchase separate product called EMC RecoverPoint to cover this lack of functionality
Limited synchronous remote-distance mirror within VPLEX (up to 100km only), no native asynchronous support, use functionality of back-end storage arrays
Provides thin provisioning to devices that don't offer this natively
Like Invista, No
SVC Split-Cluster allows concurrent read/write access of data to be accessed from hosts at two different locations several miles apart
I don't think so
PLEX-Metro, similar in concept but implemented differently
Non-disruptive tech refresh
Can upgrade or replace storage arrays, SAN switches, and even the SVC nodes software AND hardware themselves, non-disruptively
Tech refresh for storage arrays, but not for Invista CPCs
Tech refresh of back end devices, and upgrade of VPLEX software, non-disruptively. Not clear if VPLEX engines themselves can be upgraded non-disruptively like the SVC.
Heterogeneous Storage Support
Broad support of over 140 different storage models from all major vendors, including all CLARiiON, Symmetrix and VMAX from EMC, and storage from many smaller startups you may not have heard of
Invista-like. VPLEX claims to support a variety of arrays from a variety of vendors, but as far as I can find, only DS8000 supported from the list of IBM devices. Fellow blogger Barry Burke (EMC) suggests [putting SVC between VPLEX and third party storage devices] to get the heterogeneous coverage most companies demand.
Back-end storage requirement
Must define quorum disks on any IBM or non-IBM back end storage array. SVC can run entirely on non-IBM storage arrays
HP SVSP-like, requires at least one EMC storage array to hold metadata
SVC 2145-CF8 model supports up to four solid-state drives (SSD) per node that can treated as managed disk to store end-user data
Invista-like. VPLEX has an internal 30GB SSD, but this is used only for operating system and logs, not for end-user data.
In-band virtualization solutions from IBM and HDS dominate the market. Being able to migrate data from old devices to new ones non-disruptively turned out to be only the [tip of the iceberg] of benefits from storage virtualization. In today's highly virtualized server environment, being able to non-disruptively migrate data comes in handy all the time. SVC is one of the best storage solutions for VMware, Hyper-V, XEN and PowerVM environments. EMC watched and learned in the shadows, taking notes of what people like about the SVC, and decided to follow IBM's time-tested leadership to provide a similar offering.
EMC re-invented the wheel, and it is round. On a scale from Invista (zero) to SVC (ten), I give EMC's new VPLEX a six.
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!
Those that prefer to work with one-stop shopping of an IT Supermarket, with companies like IBM, HP and Dell who offer a complete set of servers, storage, switches, software and services, what we call "The Five S's".
Those that perfer shopping for components at individual specialty shops, like butchers, bakers, and candlestick makers, hoping that this singular focus means the products are best-of-breed in the market. Companies like HDS for disk, Quantum for tape, and Symantec for software come to mind.
My how the IT landscape for vendors has evolved in just the past five years! Cisco starts to sell servers, and enters a "mini-mall" alliance with EMC and VMware to offer vBlock integrated stack of server, storage and switches with VMware as the software hypervisor. For those not familiar with the concept of mini-malls, these are typically rows of specialty shops. A shopper can park their car once, and do all their shopping from the various shops in the mini-mall. Not quite "one-stop" shopping of a supermarket, but tries to address the same need.
("Who do I call when it breaks?" -- The three companies formed a puppet company, the Virtual Computing Environment company, or VCE, to help answer that question!)
Among the many things IBM has learned in its 100+ years of experience, it is that clients want choices. Cisco figured this out also, and partnered with NetApp to offer the aptly-named FlexPod reference architecture. In effect, Cisco has two boyfriends, when she is with EMC, it is called a Vblock, and when she is with NetApp, it is called a FlexPod. I was lucky enough to find this graphic to help explain the three-way love triangle.
Did this move put a strain on the relationship between Cisco and EMC? Last month, EMC announced VSPEX, a FlexPod-like approach that provides a choice of servers, and some leeway for resellers to make choices to fit client needs better. Why limit yourself to Cisco servers, when IBM and HP servers are better? Is this an admission that Vblock has failed, and that VSPEX is the new way of doing things? No, I suspect it is just EMC's way to strike back at both Cisco and NetApp in what many are calling the "Stack Wars". (See [The Stack Wars have Begun!], [What is the Enterprise Stack?], or [The Fight for the Fully Virtualized Data Center] for more on this.)
(FTC Disclosure: I am both an employee and shareholder of IBM, so the U.S. Federal Trade Commission may consider this post a paid, celebrity endorsement of the IBM PureFlex system. IBM has working relationships with Cisco, NetApp, and Quantum. I was not paid to mention, nor have I any financial interest in, any of the other companies mentioned in this blog post. )
Last month, IBM announced its new PureSystems family, ushering in a [new era in computing]. I invite you all to check out the many "Paterns of Expertise" available at the [IBM PureSystems Centre]. This is like an "app store" for the data center, and what I feel truly differentiates IBM's offerings from the rest.
The trend is obvious. Clients who previously purchased from specialty shops are discovering the cost and complexity of building workable systems from piece-parts from separate vendors has proven expensive and challenging. IBM PureFlex™ systems eliminate a lot of the complexity and effort, but still offer plenty of flexibility, choice of server processor types, choice of server and storage hypervisors, and choice of various operating systems.
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.
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!!!).
(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!
Five years ago, I sprayed coffee all over my screen from something I read on a blog post from fellow blogger Hu Yoshida from HDS. You can read what cased my reaction in my now infamous post [Hu Yoshida should know better]. Subsequently, over the years, I have disagreed with Hu on a variety of of topics, as documented in my 2010 blog post [Hu Yoshida Does It Again].
(Apparently, I am not alone, as the process of spraying one's coffee onto one's computer screen while reading other blog posts has been referred to as "Pulling a Tony" or "Doing a Tony" by other bloggers!)
Fortunately, my IBM colleague David Sacks doesn't drink coffee. Last month, David noticed that Hu had posted a graph in a recent blog entry titled [Additional Storage Performance Efficiencies for Mainframes], comparing the performance of HDS's Virtual Storage Platform (VSP) to IBM's DS8000.
For those not familiar with disk performance graphs, flatter is better, lower response time and larger IOPS are always desired. This graph implies that the HDS disk system is astonishingly faster than IBM's DS8000 series disk system. Certainly, the HDS VSP qualifies as a member of the elite [Super High-End club] with impressive SPC benchmark numbers, and is generally recognized as a device that works in IBM mainframe environments. But this new comparison graph is just ridiculous!
(Note: While SPC benchmarks are useful for making purchase decisions, different disk systems respond differently to different workloads. As the former lead architect of DFSMS for z/OS, I am often brought in to consult on mainframe performance issues in complex situations. Several times, we have fixed performance problems for our mainframe clients by replacing their HDS systems with IBM DS8000 series!)
Since Hu's blog entry contained very little information about the performance test used to generate the graph, David submitted a comment directly to Hu's blog asking a few simple questions to help IBM and Hu's readers determine whether the test was fair. Here is David's comment as submitted:
(Disclosure: I work for IBM. This comment is my own.)
I was quite surprised by the performance shown for the IBM DS8000 in the graph in your blog. Unfortunately, you provided very little detail about the benchmark. That makes it rather difficult (to say the least) to identify factors behind the results shown and to determine whether the comparison was a fair one.
Of the little information provided, an attribute that somewhat stands out is that the test appears to be limited to a single volume at least, that's my interpretation of "LDEV: 1*3390-3"? IBM's internal tests for this kind of case show far better response time and I/Os per second than the graph you published.
Here are a few examples of details you could provide to help readers determine whether the benchmark was fair and whether the results have any relevance to their environment.
What DS8000 model was the test run on? (the DS8000 is a family of systems with generations going back 8 years. The latest and fastest model is the DS8800.)
What were the hardware and software configurations of the DS8000 and VSP systems, including the number and speed of performance-related components?
What were the I/O workload characteristics (e.g., read:write ratio and block size(s))?
What was the data capacity of each volume? (Allocated and used capacity.)
What were the cache sizes and cache hit ratios for each system? (The average I/O response times under 1.5 milliseconds for each system imply the cache hit ratios were relatively high.)
How many physical drives were volumes striped across in each system?"
Unlike my blog on IBM, HDS bloggers like Hu are allowed to reject or deny comments before they appear on his blog post. We were disappointed that HDS never posted David's comment nor responded to it. That certainly raises questions about the quality of the comparison.
So, perhaps this is yet another case of [Hitachi Math], a phrase coined by fellow blogger Barry Burke from EMC back in 2007 in reference to outlandish HDS claims. My earliest mention was in my blog post [Not letting the Wookie Win].
By the way, since the test was about z/OS Extended Address Volumes (EAV), it is worth mentioning that IBM's DS8700 and DS8800 support 3390 volume capacities up to 1 TB each, while the HDS VSP is limited to only 223 GB per volume. Larger volume capacities help support ease-of-growth and help reduce the number of volumes storage administrators need to manage; that's just one example of how the DS8000 series continues to provide the best storage system support for z/OS environments.
Personally, I am all for running both IBM and HDS boxes side-by-side and publishing the methodology, the workload characteristics, the configuration details, and the results. Sunshine is always the best disinfectant!
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.
The new [IBM System Storage Tape Controller 3592 Model C07] is an upgrade to the previous C06 controller. Like the C06, the new 3592-C07 can have up to four FICON (4Gbps) ports, four FC ports, and connect up to 16 drives. The difference is that the C07 supports 8Gbps speed FC ports, and can support the [new TS1140 tape drives that were announced on May 9]. A cool feature of the C07 is that it has a built-in library manager function for the mainframe. On the previous models, you had to have a separate library manager server.
Crossroads ReadVerify Appliance (3222-RV1)
IBM has entered an agreement to resell [Crossroads ReadVerify Appliance], or "RV1" for short. The RV1 is a 1U-high server with software that gathers information on the utilization, performance and health for a physical tape environment, such as an IBM TS3500 Tape Library. The RV1 also offers a feature called "ArchiveVerify" which validates long-term retention archive tapes, providing an audit trail on the readability of tape media. This can be useful for tape libraries attached behind IBM Information Archive compliance storage solution, or the IBM Scale-Out Network Attached Storage (SONAS).
As an added bonus, Crossroads has great videos! Here's one, titled [Tape Sticks]
Linear Tape File System (LTFS) Library Edition Version 2.1
While the hardware is all refreshed, the overall "scale-out" architecture is unchanged. Kudos to the XIV development team for designing a system that is based entirely on commodity hardware, allowing new hardware generations to be introduced with minimal changes to the vast number of field-proven software features like thin provisioning, space-efficient read-only and writeable snapshots, synchronous and asynchronous mirroring, and Quality of Service (QoS) performance classes.
The new XIV Gen3 features an Infiniband interconnect, faster 8Gbps FC ports, more iSCSI ports, faster motherboard and processors, SAS-NL 2TB drives, 24GB cache memory per XIV module, all in a single frame IBM rack that supports the IBM Rear Door Heat Exchanger. The results are a 2x to 4x boost in performance for various workloads. Here are some example performance comparisons:
Disclaimer: Performance is based on measurements and projections using standard IBM benchmarks in a controlled environment. The actual throughput that any user will experience will vary depending upon considerations such as the amount of multiprogramming in the user's job stream, the I/O configuration, the storage configuration, and the workload processed. Therefore, no assurance can be given that an individual user will achieve throughput improvements equivalent to the performance ratios stated here. Your mileage may vary.
In a Statement of Direction, IBM also has designed the Gen3 modules to be "SSD-ready" which means that you can insert up to 500GB of Solid-State drive capacity per XIV module, up to 7.5TB in a fully-configured 15 module frame. This SSD would act as an extension of DRAM cache, similar to how Performance Accelerator Modules (PAM) on IBM N series.
IBM will continue to sell XIV Gen2 systems for the next 12-18 months, as some clients like the smaller 1TB disk drives. The new Gen3 only comes with 2TB drives. There are some clients that love the XIV so much, that they also use it for less stringent Tier 2 workloads. If you don't need the blazing speed of the new Gen3, perhaps the lower cost XIV Gen2 might be a great fit!
As if I haven't said this enough times already, the IBM XIV is a Tier-1, high-end, enterprise-class disk storage system, optimized for use with mission critical workloads on Linux, UNIX and Windows operating systems, and is the ideal cost-effective replacement for EMC Symmetrix VMAX, HDS USP-V and VSP, and HP P9000 series disk systems, . Like the XIV Gen2, the XIV Gen3 can be used with IBM System i using VIOS, and with IBM System z mainframes running Linux, z/VM or z/VSE. If you run z/OS or z/TPF with Count-Key-Data (CKD) volumes and FICON attachment, go with the IBM System Storage DS8000 instead, IBM's other high-end disk system.
Continuing my post-week coverage of the [Data Center 2010 conference], Thursday morning had some interesting sessions for those that did not leave town last night.
Interactive Session Results
In addition to the [Profile of Data Center 2010] that identifies the demographics of this year's registrants, the morning started with highlights of the interactive polls during the week.
External or Heterogeneous Storage Virtualization
The analyst presented his views on the overall External/Heterogeneous Storage Virtualization marketplace. He started with the key selling points.
Avoid vendor lock-in. Unlike the IBM SAN Volume Controller, many of the other storage virtualization products result in vendor lock-in.
Leverage existing back-end capacity. Limited to what back-end storage devices are supported.
Simplify and unify management of storage. Yes, mostly.
Lower storage costs. Unlike the IBM SAN Volume Controller, many using other storage virtualization discover an increase in total storage costs.
Migration tools. Yes, as advertised.
Consolidation/Transition. Yes, over time.
Better functionality. Potentially.
Shortly after several vendors started selling external/heterogeneous storage virtualization solutions, either as software or pre-installed appliances, major storage vendors that were caught with their pants down immediately started calling everything internally as also "storage virtualization" to buy some time and increase confusion.
While the analyst agreed that storage virtualization simplifies the view of storage from the host server side, it can complicate the management of storage on the storage end. This often comes up at the Tucson Briefing Center. I explain this as the difference between manual and automatic transmission cars. My father was a car mechanic, and since he is the sole driver and sole mechanic, he prefers manual transmission cars, easier to work on. However, rental car companies, such as Hertz or Avis, prefer automatic transmission cars. This might require more skills on behalf of their mechanics, but greatly simplifies the experience for those driving.
The analyst offered his views on specific use cases:
Data Migration. The analyst feels that external virtualization serves as one of the best tools for data migration. But what about tech refresh of the storage virtualization devices themselves? Unlike IBM SAN Volume Controller, which allows non-disruptive upgrades of the nodes themselves, some of the other solutions might make such upgrades difficult.
Consolidation/Transition. External virtualization can also be helpful, depending on how aggressive the schedule for consolidation/transition is performed.
Improved Functionality/Usability. IBM SAN Volume Controller is a good example, an unexpected benefit. Features like thin provisioning, automated storage tiering, and so on, can be added to existing storage equipment.
The analyst mentioned that there were different types of solutions. The first category were those that support both internal storage and external storage virtualization, like the HDS USP-V or IBM Storwize V7000. He indicated that roughly 40 percent of HDS USP-V are licensed for virtualization. The second category were those that support external virtualization only, such as IBM SAN Volume Controller, HP Lefthand and SVSP, and so on. The third category were software-only Virtual Guest images that could provide storage virtualization capabilities.
The analyst mentioned EMC's failed product Invista, which sold less than 500 units over the past five years. The low penetration for external virtualization, estimated between 2-5 percent, could be explained from the bad taste that left in everyone considering their options. However, the analyst predicts that by 2015, external virtualization will reach double digit marketshare.
Having a feel for the demographics of the registrants, and specific interactive polling in each meeting, provides a great view on who is interested in what topic, and some insight into their fears and motivations.
This week, Hitachi Ltd. announced their next generation disk storage virtualization array, the Virtual Storage Platform, following on the success of its USP V line. It didn't take long for fellow blogger Chuck Hollis (EMC) to comment on this in his blog post [Hitachi's New VSP: Separating The Wheat From The Chaff]. Here are some excerpts:
"Well, we all knew that Hitachi (through HDS and HP) would be announcing some sort of refresh to their high-end storage platform sooner or later.
As EMC is Hitachi's only viable competitor in this part of the market, I think people are expecting me to say something.
If you're a high-end storage kind of person, your universe is basically a binary star: EMC and Hitachi orbiting each other, with the interesting occasional sideshow from other vendors trying to claim relevance in this space."
Chuck implies that neither Hewlett-Packard (HP) nor Hitachi Data Systems (HDS) as vendors provide any value-add from the box manufactured by Hitachi Ltd. so combines them into a single category. I suspect the HP and HDS folks might disagree with that opinion.
When I reminded Chuck that IBM was also a major player in the high-end disk space, his response included the following gem:
"Many of us in the storage industry believe that IBM currently does not field a competitive high-end storage platform. IDC market share numbers bear out this assertion, as you probably know."
While Chuck is certainly entitled to his own beliefs and opinions, believing the world is flat does not make it so. Certainly, I doubt IDC or any other market research firm has put out a survey asking "Do you think IBM offers a competitive high-end disk storage platform?" Of course, if Chuck is basing his opinion on anecdotal conversations with existing EMC customers, I can certainly see how he might have formed this misperception. However, IDC market share numbers don't support Chuck's assertion at all.
There is no industry-standard definition of what is a "high-end" or "enterprise-class" disk system. Some define high-end as having the option for mainframe attachment via ESCON and/or FICON protocol. Others might focus on features, functionality, scalability and high 99.999+ percent availability. Others insist high-end requires block-oriented protocols like FC and iSCSI, rather than file-based protocols like NAS and CIFS.
For the most demanding mission-critical mix of random and sequential workloads, IBM offers the [IBM System Storage DS8000 series] high-end disk system which connects to mainframes and distributed servers, via FCP and FICON attachment, and supports a variety of drive types and RAID levels. The features that HP and HDS are touting today for the VSP are already available on the IBM DS8000, including sub-LUN automatic tiering between Solid-State drives and spinning disk, called [Easy Tier], thin provisioning, wide striping, point-in-time copies, and long distance synchronous and asynchronous replication.
There are lots of analysts that track market share for the IT storage industry, but since Chuck mentions [IDC] specifically, I reviewed the most recent IDC data, published a few weeks ago in their "IDC Worldwide Quarter Disk Storage Tracker" for 2Q 2010, representing April 1 to June 30, 2010 sales. Just in case any of the rankings have changed over time, I also looked at the previous four quarters: 2Q 2009, 3Q 2009, 4Q 2009 and 1Q 2010.
(Note: IDC considers its analysis proprietary, out of respect for their business model I will not publish any of the actual facts and figures they have collected. If you would like to get any of the IDC data to form your own opinion, contact them directly.)
In the case of IDC, they divide the disk systems into three storage classes: entry-level, midrange and high-end. Their definition of "high-end" is external RAID-protected disk storage that sells for $250,000 USD or more, representing roughly 25 to 30 percent of the external disk storage market overall. Here are IDC's rankings of the four major players for high-end disk systems:
By either measure of market share, units (disk systems) or revenue (US dollars), IDC reports that IBM high-end disk outsold both HDS and HP combined. This has been true for the past five quarters. If a smaller start-up vendor has single digit percent market share, I could accept it being counted as part of Chuck's "occasional sideshow from other vendors trying to claim relevance", but IBM high-end disk has consistently had 20 to 30 percent market share over the past five quarters!
Not all of these high-end disk systems are connected to mainframes. According to IDC data, only about 15 to 25 percent of these boxes are counted under their "Mainframe" topology.
Chuck further writes:
"It's reasonable to expect IBM to sell a respectable amount of storage with their mainframes using a protocol of their own design -- although IBM's two competitors in this rather proprietary space (notably EMC and Hitachi) sell more together than does IBM."
The IDC data doesn't support that claim either, Chuck. By either measure of market share, units (disk systems) or revenue (US dollars), IDC reports that IBM disk for mainframes outsold all other vendors (including EMC, HDS, and HP) combined. And again, this has been true for the past five quarters. Here is the IDC ranking for mainframe disk storage:
IBM has over 50 percent market share in this case, primarily because IBM System Storage DS8000 is the industry leader in mainframe-related features and functions, and offers synergy with the rest of the z/Architecture stack.
So Chuck, I am not picking a fight with you or asking you to retract or correct your blog post. Your main theme, that the new VSP presents serious competition to EMC's VMAX high-end disk arrays, is certainly something I can agree with. Congratulations to HDS and HP for putting forth what looks like a viable alternative to EMC's VMAX.
To learn more about IBM's upcoming products, register for next week's webcast "Taming the Information Explosion with IBM Storage" featuring Dan Galvan, IBM Vice President, and Steve Duplessie, Senior Analyst and Founder of Enterprise Storage Group (ESG).