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Tony Pearson is a Master Inventor, Senior IT Architect and Event Content Manager for [IBM Systems for IBM Systems Technical University] events. With over 30 years with IBM Systems, Tony is frequent traveler, speaking to clients at events throughout the world.
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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!
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 coverage of my week in Washington DC for the annual [2010 System Storage Technical University], I attended several XIV sessions throughout the week. There were many XIV sessions. I could not attend all of them. Jack Arnold, one of my colleagues at the IBM Tucson Executive Briefing Center, often presents XIV to clients and Business Partners. He covered all the basics of XIV architecture, configuration, and features like snapshots and migration. Carlos Lizarralde presented "Solving VMware Challenges with XIV". Ola Mayer presented "XIV Active Data Migration and Disaster Recovery".
Here is my quick recap of two in particular that I attended:
XIV Client Success Stories - Randy Arseneau
Randy reported that IBM had its best quarter ever for the XIV, reflecting an unexpected surge shortly after my blog post debunking the DDF myth last April. He presented successful case studies of client deployments. Many followed a familiar pattern. First, the client would only purchase one or two XIV units. Second, the client would beat the crap out of them, putting all kinds of stress from different workloads. Third, the client would discover that the XIV is really as amazing as IBM and IBM Business Partners have told them. Finally, in the fourth phase, the client would deploy the XIV for mission-critical production applications.
A large US bank holding company managed to get 5.3 GB/sec from a pair of XIV boxes for their analytics environment. They now have 14 XIV boxes deployed in mission-critical applications.
A large equipment manufacturer compared the offerings among seven different storage vendors, and IBM XIV came out the winner. They now have 11 XIV boxes in production and another four boxes for development/test. They have moved their entire VMware infrastructure to IBM XIV, running over 12,000 guest instances.
A financial services company bought their first XIV in early 2009 and now has 34 XIV units in production attached to a variety of Windows, Solaris, AIX, Linux servers and VMware hosts. Their entire Microsoft Exchange was moved from HP and EMC disk to IBM XIV, and experienced noticeable performance improvement.
When a University health system replaced two competitive disk systems with XIV, their data center temperature dropped from 74 to 68 degrees Fahrenheit. In general, XIV systems are 20 to 30 percent more energy efficient per usable TB than traditional disk systems.
A service provider that had used EMC disk systems for over 10 years evaluated the IBM XIV versus upgrading to EMC V-Max. The three year total cost of ownership (TCO) of EMC's V-Max was $7 Million US dollars higher, so EMC counter-proposed CLARiiON CX4 instead. But, in the end, IBM XIV proved to be the better fit, and now the customer is happy having made the switch.
The manager of an information communications technology service provider was impressed that the XIV was up and running in just a couple of days. They now have over two dozen XIV systems.
Another XIV client had lost all of their Computer Room Air Conditioning (CRAC) units for several hours. The data center heated up to 126 degrees Fahrenheit, but the customer did not lose any data on either of their two XIV boxes, which continued to run in these extreme conditions.
Optimizing XIV Performance - Brian Cormody
This session was an update from the [one presented last year] by Izhar Sharon. Brian presented various best practices for optimizing the performance when using specific application workloads with IBM XIV disk systems.
Oracle ASM: Many people allocate lots of small LUNs, because this made sense a long time ago when all you had was just a bunch of disks (JBOD). In fact, many of the practices that DBAs use to configure databases across disks become unnecessary with XIV. Wth XIV, you are better off allocating a few number of very large LUNs from the XIV. The best option was a 1-volume ASM pool with 8MB AU stripe. A single LUN can contain multiple Oracle databases. A single LUN can be used to store all of the logs.
VMware: Over 70 percent of XIV customers use it with VMware. For VMFS, IBM recommends allocating a few number of large LUNs. You can specify the maximum of 2181 GB. Do not use VMware's internal LUN extension capability, as IBM XIV already has thin provisioning and works better to allow XIV to do this for you. XIV Snapshots provide crash-consistent copies without all the VMware overhead of VMware Snapshots.
SAP: For planning purposes, the "SAPS" unit equates roughly to 0.4 IOPS for ERP OLTP workloads, and 0.6 IOPS for BW/BI OLAP workloads. In general, an XIV can deliver 25-30,000 IOPS at 10-15 msec response time, and 60,000 IOPS at 30 msec response time. With SAP, our clients have managed to get 60,000 IOPS at less than 15 msec.
Microsoft Exchange: Even my friends in Redmond could not believe how awesome XIV was during ESRP testing. Five Exchange 2010 servers connected two a pair of XIV boxes using the new 2TB drawers managed 40,000 mailboxes at the high profile (0.15 IOPS per mailbox). Another client found four XIV boxes (720 drives) was able to handle 60,000 mailboxes (5GB max), which would have taken over 4000 drives if internal disk drives were used instead. Who said SANs are obsolete for MS Exchange?
Asynchronous Replication: IBM now has an "Async Calculator" to model and help design an XIV async replication solution. In general, dark fiber works best, and MPLS clouds had the worst results. The latest 10.2.2 microcode for the IBM XIV can now handle 10 Mbps at less than 250 msec roundtrip. During the initial sync between locations, IBM recommends setting the "schedule=never" to consume as much bandwidth as possible. If you don't trust the bandwidth measurements your telco provider is reporting, consider testing the bandwidth yourself with [iPerf] open source tool.
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.