VMware's PSA is awash in abbreviations and options

I am often questioned during my Storage for Virtual Environments seminar presentations about VMware’s Pluggable Storage Architecture (PSA). This system is fairly straightforward and concept: VMware provides native multipathing support for a variety of storage arrays, and allows third parties to substitute their own plug-ins at various points in the stack. But the profusion of acronyms and third-party options makes it difficult for end-users to figure out what is going on. In an effort to help, I present here another entry in my “VMware storage features in plain English” series.

Note: I am more of a storage guy than a virtualization expert. I consider myself one of those end-users who have had trouble figuring out what’s going on with PSA specifically, in VMware storage features in general. I welcome comments and suggestions for corrections or improvements to this and all of my articles. Thanks for your help!

Introducing Pluggable Storage Architecture (PSA)

Pluggable storage architecture was one of the major enhancements introduced in vSphere 4. Functionally similar to Microsoft’s MPIO stack for Windows, PSA includes native multipathing support and allows vendors to plug in their own advanced features.

I find the VMware diagram confusing. Is mine more or less accurate and readable?

The ESX kernel (VMkernel) walks down through three layers when communicating with storage:

1. In the top layer, VMware native NMP or third-party MPP software decides which SATP to use, or whether to use the native interface. MASK_PATH also operates at this layer.
2. The SATP layer includes native generic path selection (active/active, active/passive), standard ALUA, as well as allowing third-party plugins (SATP) to override its behavior. The SATP monitors these paths, reports changes, and initiates fail-over on the array as needed.
3. At the PSP layer, software decides which physical channel to use for I/O requests.

There are three types of PSA plugins for vSphere 4:

1. Storage Array Type Plug-In (SATP)
2. Path Selection Plug-in (PSP)
3. A complete third-party multipathing software stack (MPP)

As is the case with VAAI, VMware includes a number of third-party plug-ins in the ESXi install. Users can simply activate many of these according to their needs, though some require additional fees and licensing.

Storage Array Type Plug-in (SATP) List

Storage Array Type Plug-Ins (SATPs) to the VMware Pluggable Storage Architecture multipathing solution for the specific characteristics of the storage array. This is very important, since each storage array design differs substantially in detail and support, especially when it comes to load-balancing and failover between controllers, ports, and paths. So it is critical for VMware to have developed a standard interface to communicate with arrays.

SATPs allow load balancing across multiple paths, intelligent path selection, and over troubled conditions such as “chatter”, when passed rapidly fail back and forth between controllers.

The SATP has critical tasks to perform in the PSA stack:

1. Decide which method of communication to use with the storage (PSA or native)
2. Monitor the health of the physical I/O channels or paths
3. Report any changes in the state of the paths up the stack
4. Perform actions required to fail over storage between controllers on the array

VMware vSphere includes a variety of generic plugins for storage arrays. I’ve identified the following:

• VMW_SATP_LOCAL – Local SATP for direct-attached devices
• VMW_SATP_DEFAULT_AA – Generic for active/active arrays
• VMW_SATP_DEFAULT_AP – Generic for active/passive arrays
• VMW_SATP_ALUA – Asymmetric Logical Unit Access-compliant arrays

Although I have sometimes seen other SATP plug-ins mentioned, the following plug-ins are all that are listed in the VMware ESX Hardware Compatibility List.

• VMW_SATP_LSI – LSI/NetApp arrays from Dell, HDS, IBM, Oracle, SGI
• VMW_SATP_SVC – IBM SVC-based systems (SVC, V7000, Actifio)
• VMW_SATP_CX – EMC/Dell CLARiiON  and Celerra (also VMW_SATP_ALUA_CX)
• VMW_SATP_SYMM – EMC Symmetrix DMX-3/DMX-4/VMAX, Invista
• VMW_SATP_INV – EMC Invista and VPLEX
• VMW_SATP_EQL – Dell EqualLogic systems

EMC PowerPath and HDS HDLM also support a variety of storage arrays, but I would classify these as full MPP replacements for PSA, rather than SATP plug-ins.

You can see which SATP plug-ins are available using the following esxcli command:

esxcli nmp satp list

Path selection plug-in (PSP) List

In contrast to the diversity of VAAI and SATP plug-ins, the universe of path selection plug-ins is fairly small. Most storage arrays are supported with either Most Recently Used (MRU) or Fixed path selection approaches. Many also support Round Robin (RR) path selection. The only vendor with a specific PSP that is not also part of a full MPP (like EMC PowerPath or HDS HDLM) is Dell, which offers a special routed path selection plug-in for the EqualLogic iSCSI arrays.

• VMW_PSP_MRU – Most-Recently Used (MRU) – Supports hundreds of storage arrays
• VMW_PSP_FIXED – Fixed – Supports hundreds of storage arrays
• VMW_PSP_RR – Round-Robin – Supports dozens of storage arrays
• DELL_PSP_EQL_ROUTED – Dell EqualLogic iSCSI arrays

As mentioned, EMC PowerPath also offers path selection as a plug-in in addition to the full MPP stack. Many other vendors offer unique path selection plug-ins, over 100 in total, but these are not specifically called out in the VMware HCL apart from their existence. I would love to learn more about them, however.

You can see which SATP plug-ins are available using the following esxcli command:

esxcli nmp psp list

Tell Me More About PSA!

As mentioned above, I am by no means an expert in VMware Pluggable Storage Architecture. Rather, I am interested in learning more and passing on this knowledge to others. I welcome your comments and feedback, and especially your corrections to the information presented here. I will try to keep this page updated as new versions of vSphere are introduced and as I learn more about this technology. Thank you for your help and understanding!

Further Reading:

• What’s New in VMware vSphere 4: Storage
• Next-Generation ESX Storage: A Pluggable Core Storage Architecture
• Storage Changes in the VMware vSphere 4 Family
• Pluggable Storage Architecture, exploring the next version of ESX/vCenter
• Vmware vSphere 4.1 PSA (Pluggable Storage Architecture) Understanding
• Explain the Pluggable Storage Architecture (PSA) Layout

© sfoskett for Stephen Foskett, Pack Rat, 2011. | VMware PSP and SATP in Plain English
This post was categorized as Enterprise storage, Everything, Virtual Storage. Each of my categories has its own feed if you'd like to filter out or focus on posts like this.

What is Multipath? And Why?

The good old days: One device, one path

In the beginning, computers connected to peripherals and other computers through a single bus or channel and life was easy. Although one might mistake the names of the dominant printer connection (parallel) for some kind of multipath system when compared to the modem connection (serial), this was not the case. Only the bits traveled in parallel – the logical connection was a simple single path.

Early-90's servers might confuse admins with two SCSI connections to a single device

Then things got complicated. The SCSI protocol allowed for multiple devices in a chain, and even for two different “initiators” (computers or controllers) to interact with these “targets”. Some folks even dual-attached devices to a single computer with multiple controllers.

Why would one device and one computer need more than one connection? It boils down to two factors:

1. Performance – I/O channels have typically been slower than the computer could handle, so multiple channels might be used to increase the amount of data that can flow in and out.
2. Reliability – If one connection failed, the other might still be usable, reducing the risk of an outage.

Late-90's enterprise systems might have four or more paths to a single storage array

Pretty soon, enterprise computer architecture had gotten incredibly complex. I remember connecting a massive HP V-class server to an EMC Symmetrix with eight separate Fibre Channel cables. Each disk “LUN” showed up twice, and we had hundreds of them. We managed all of these virtual storage paths using HP’s PVLinks dynamic multipathing software. We used Veritas DMP and EMC PowerPath to do pretty much the same thing on Solaris and other UNIX systems.

Active/Passive to Active/Active

The earliest path management software provided two incredibly important functions: It figured out which of the SCSI targets it saw were actually different names for the same one, and it allowed the operating system to choose one and fail over to the other in case of an interruption. These were Active/Passive links – no matter how many paths were presented (and Fibre Channel switches sometimes presented eight or more), only one was active at any one time.

Modern systems have abstracted and virtual I/O channels, making path management much more important

But the EMC Symmetrix and similar high-end storage systems changed all this. Symmetrix storage was fully virtualized – the presentation of LUNs to servers was entirely disconnected from the actual disks and RAID sets in the array. This meant the Symmetrix could handle I/O requests across different paths and controllers for the same LUN. EMC and the rest responded with Active/Active path management software, allowing I/O to travel in parallel for the first time.

How is Dual Active Different?

Not everything called Active/Active is created equal. In fact, many supposed Active/Active setups really shouldn’t be called that since they don’t use both paths for all data. Instead, I like to call these Dual Active – both paths are active but with different data.

Consider the differences between the following two solutions:

A true active/active setup uses all paths for all data all the time

A "dual active" setup uses both paths, but each target is directed to one or the other

See the difference? Although the paths are active in both cases, they are not the same. Both approaches have merit, and neither is inherently superior, but they should have different names applied. Even active/passive has its place, since simplicity is often a virtue.

Dual Active Outside Storage

These same concepts apply outside the field of storage and I/O. Many server clustering systems use the same terminology, right down to the misapplication of “active/active” when “dual active” is more appropriate. It’s easy to miss the significance of this difference, but it can make more of an impact in clustering since CPU workloads are harder to balance.

Let me know what you think. If there is interest, I might dive into path management strategies like round robin!

© sfoskett for Stephen Foskett, Pack Rat, 2010. | Multipath: Active/Passive, Dual Active, and Active/Active
This post was categorized as Computer History, Enterprise storage, Everything, Gestalt IT, Virtual Storage. Each of my categories has its own feed if you'd like to filter out or focus on posts like this.

Driving Massive I/O

Chuck Hollis treated us to a discussion of vSphere as an I/O Engine on his blog this morning with some background on multipath IO (MPIO for short), but I’m not sure he did the topic justice. In my opinion, server virtualization is the greatest I/O driver ever brought into the data center, and it messes with all of our preconceived notions about I/O at the same time.

What’s so special about server virtualization?

1. Hypervisors concentrate I/O, shifting loads that were formerly distributed to a large number of I/O channels into a far fewer channels. Picture 10 servers doing what they do. Now put all 10 in a single physical box. All of their storage access must now share a bus, a host adapter, a cable, and perhaps a LUN on the storage system. It’s the difference between lemonade and lemon juice!
2. Hypervisors randomize I/O, chunking everything up and mixing it together. Forget about the carefully-designed read-ahead algorithms and caching used in enterprise storage – VMware, Hyper-V and the rest throw those expectations out the window! Virtualization is a blender – it grinds up your lemons, skin, seeds, and all!
3. Hypervisors demand low I/O latency, forcing infrastructure to get quicker, not just faster. This is one reason that caching, solid state disks, and 10 GbE are going to be huge in virtual environments – all reduce latency by orders of magnitude! As any car guy will tell you, quick and fast are two very different things!

The upshot of all of this is that virtual servers are very very hard to satisfy when it comes to I/O. And the “back end” has always been a bit of a bottleneck for virtualization software. Now we have VMware claiming that vSphere 4 can push over 300,000 I/O operations per second (IOPS) without resorting to VMDirectPath and similar “cheater” measures. Of course not all IOPS are equal, and I doubt that that 300k number would hold up with a real-world workload, but it’s impressive nonetheless!

A Brief History of MPIO

Let’s turn back to multipath I/O. PowerPath/VE is just the latest in a long line of path managers, not all of which have been well-loved. Back in my HP-UX days I learned to make the most of PVlinks, the native path management on that operating system. It wasn’t always easy to get it to work well, but it sure was nice to have a path manager built into the operating system! Veritas also offered a multi-platform path manager, DMP, which worked with a variety of array types. Back in the day, both were limited to simple failover and lacked the “intelligence” to deal with the peculiarities of the weird storage arrays we learned to not hate.

Array-specific path managers from storage vendors were much more successful. CLARiiONs used ATF, Hitachi arrays used HDLM, IBM had SDD, and of course EMC had PowerPath. EMC introduced PowerPath in 1997, the software reportedly having been developed by Conley Corporation, which EMC acquired the next year and turned into its Cambridge (MA) development center. After acquiring Data General, EMC adapted PowerPath to support CLARiiON, pushing ATF off stage right. Then they kept right on developing the software, adding support for IBM, HDS, and HP arrays and data migration.

Meanwhile, Microsoft decided that HP and Veritas were on to something when they developed standard path management software, so they began working on a standard multi-path IO (MPIO) driver for Windows. But Microsoft learned a thing or two from the mediocre device support in those old solutions, so they decided to allow vendors to plug their own smarts into the standard Windows Server 2000/2003 MPIO framework. Microsoft provided basic failover capability and third parties, including EMC, wrote their own device-specific modules (DSMs). This MPIO support evolved and spread, standard on Microsoft’s iSCSI initiator and Hyper-V virtualization platform. PowerPath 5.2.1 for Windows already supported Hyper-V thanks to this.

PowerPath and VMware PSA

VMware also learned a thing or two from HP and Microsoft. Although basic path failover support has been included in ESX for years, vSphere 4 takes it to a new level with pluggable storage architecture (PSA). Every version of ESX 4 includes native multipathing (NMP), but Enterprise Plus licensees can use vendor-supplied plugins to enable more advanced path management. As I noted on Tuesday, there are two three different levels of path selection: Basic path-selection plugins (PSPs), more advanced storage array type plugins (SATPs), and complete multi-path plugins (MPPs).

This is what EMC has introduced: An MPP for vSphere 4 called PowerPath/VE. Like the DSM for Windows MPIO, PowerPath/VE for vSphere slots right into an existing MPIO framework and enables advanced path selection and load balancing without mucking with the internals of the hypervisor. PowerPath/VE has all sorts of smarts in it. It has eight different predictive load balancing policies, proactive disconnect, bus testing, and HBA monitoring.

Super VMware guy Chad Sakac described PowerPath/VE as part of the launch. He notes that EMC is first out of the gate with a multipathing plugin for vSphere, but I suspect that just about every vendor will release similar functionality pretty quickly. In particular I expect support to come from NetApp and 3PAR, since they’re so interested in VMware support.

Licensing Questions

One thing really stuck out in the vSphere launch: PSA is only included in the top-of-the-line Enterprise Plus license. Presumably, this means that, in addition to paying for a PowerPath/VE license, users will have to spring for maximum ESX, too. This is a dumb move, if you ask me. Microsoft made MPIO successful by giving it away with every copy of Windows. They even included it in the free iSCSI initiator download. VMware, in contrast, seems to be actively limiting PSA’s usefulness to the top tier of users. If it was up to me, I would set the VMware MPIO free!

I’m working with EMC and VMware to determine the extent of the NMP/PSA/PowerPath licensing mess. I’ll update this post as I find out the answers!

1. Does every edition of ESX 4 include the basic VMware native multipathing (NMP)?
2. Can one use a vendor-supplied PSA plugin like PowerPath/VE without an enterprise plus license?
3. Does it matter (to licensing) if the plugin is a PSP or an SATP?
4. If “no” to 2 or 3, can PSA be added separately without the plus license if someone wants to use something like PowerPath/VE?

Update: I received a nice email from an EMC engineer correcting me about the plugin types. This kind of open communication is why the web is so great! It turns out that PowerPath/VE is a sort of super plugin called an MPP, not “just” an SATP or PSP. I’ve updated the section above!

© sfoskett for Stephen Foskett, Pack Rat, 2009. | PowerPath To The Virtual People
This post was categorized as Computer History, Enterprise storage, Gestalt IT, Virtual Storage. Each of my categories has its own feed if you'd like to filter out or focus on posts like this.

For more information on earlier updates, see my articles:

• Storage Fixes in VMware ESX Server 3.5 Update 2
• Storage Changes in VMware ESX 3.5 Update 3
• Storage Changes in VMware ESX 3.5 Update 4
  

One first step is VMware’s whitepaper, “What’s New in VMware vSphere 4: Storage“.

Licensing and Availability of Features

The most important change at a glance is in the licensing model for VMware.

• A new low-end “standard” level includes all of the components a small business might need, including thin provisioning of storage, at a very attractive price.
• The “advanced” level includes advances in the area of data protection.
• At the “enterprise” level, live migration of storage is enabled.
• Top of the heap is “enterprise plus”, which enables the intriguing plug-in third-party multipathing support previously rumored.
• Enterprise customers with current support will get vStorage thin provisioning and data protection when they upgrade.

Each step up the licensing ladder enables important new storage features (source: VMware)

Thin Provisioning

One of the most widespread storage features is native thin provisioning. VMware ESX 4 will allocate storage in 1 MB chunks as capacity is used. This isn’t really completely new – similar support was enabled by default for virtual disks on NFS in VI 3, and thin provisioning could be enabled on the command line for block-based storage as well. It was also present in VMware’s desktop products, including my own copy of Fusion. And ESX allows thick-to-thin conversion during Storage VMotion.

The difference with vSphere 4 is that thin provisioning is fully supported and integrated into every version of ESX. Although many storage arrays now also offer thin storage, the addition of native, integrated thin provisioning right in ESX is huge. This alone will be a major capacity (and thus, cost) savings feature! VMware claims 50% storage savings in their lab tests.

Dynamic Expansion of VMFS Volumes

VMFS volumes can now grow (and, in some cases, shrink) online without resorting to spanning to a new LUN. Under vSphere 4, VMFS volumes can grow to take advantage of expanded LUNs (up to 2 TB per LUN). The old method still works as well, and multi-LUN spanned VMFS volumes can grow when any of their LUNs is expanded.

Enhanced Storage VMotion

Like thin provisioning, Storage VMotion has been elevated to first-class status, supported just about everywhere you’d want it. It’s in all the likely spots within vCenter.

Storage VMotion gives serious storage flexibility now, enabling (almost) any-to-any migration of VMFS volumes: Pick up a Fibre Channel, iSCSI, or NFS disk image and move it to another datastore running any of those protocols to convert live. And you can do thick-to-thin provisioning at the same time.

Under the hood, the whole infrastructure has been revised. Storage VMotion leverages VMware’s change block tracking instead of disk snapshots now, speeding up the migration process and reducing the (formerly excessive) memory and CPU requirements of Storage VMotion in 3.5. This is the same technology leveraged by vSphere’s High Availability features, by the way.

Pluggable Storage Architecture (PSA)

Only “Enterprise Plus” licensees will get to use it, but the vSphere family also sports a new pluggable storage architecture (PSA) which will initially be leveraged to deliver vendor-specific multipath support. Note that the native multipath support in vSphere continues to be a basic round-robin or fail-over system – it will not dynamically load balance I/O across multiple paths or make more intelligent decisions about which paths to use.

vSphere 4's Pluggable Storage Architecture allows third-party developers to replace ESX's storage I/O stack (source: VMware)

As you may gather from this VMware illustration (but would probably miss since it’s not all that comprehensible), there are two classes of third-party plug-ins:

1. Basic path-selection plugins (PSPs) will merely optimize the choice of which path to use, ideal for active/passive type arrays
2. Full storage array type plugins (SATPs) will allow load balancing across multiple paths in addition to path selection for active/active arrays

EMC also announced PowerPath/VE for vSphere, integrating their popular multi-platform path management software directly into ESX. It’s not clear at this point whether PowerPath will require an Enterprise Plus license (or if it will come with one) or if it will work with all editions, but I’m sure that will be clarified soon. My EMC contacts do tell me that PowerPath/VE is licensed on a per-socket basis (like VMware of yore) and that EMC sales reps have some room to get creative on licensing.

iSCSI Software Initiator Enhancements

It’s harder to claim it as a new feature, but the iSCSI software initiator has also been tweaked and tuned to use less CPU time and deliver better throughput. The iSCSI configuration process has also been smoothed out so one no longer needs to have a live Service Console connection in order to communicate with an iSCSI target. And changes made in the general tab are now global, so they’ll propagate down to each target. Bi-directional CHAP is also added, so the target can now be authenticated in addition to the initiator.

vSphere also includes a paravirtualized iSCSI driver (PVSCSI) which works like vmxnet to present a higher-performance iSCSI adapter within certain supported guest OSes.

More information on multipathing iSCSI can be found at Yellow Bricks and in Chad Sakac’s mega-post on the topic.

High-Performance I/O

vSphere really pours on the I/O power. They claim a 3x increase, to “over 300,000 I/O operations per second”, but mentioned in the launch that they’ve gotten to 400,000 in some workloads. This is really amazing, and if it’s true in real-world use means that VMware ESX can now host just about any application you can think of.

It’s funny, but just a few weeks before the announcement VMware’s Chief Data Center architect, Scott Davis, told me at Storage Networking World that vSphere would double I/O performance. I thought this was a bold statement at the time, but VMware went further in their official documents, claiming 3x improvement. Now we have an on-stage admission that it could be up to 4x! This is serious stuff, folks: Can VMware really do 400,000 IOPS?

One question is whether these IOPS improvements require the new VMDirectPath I/O for Storage, which binds a physical Fibre Channel HBA to a single guest OS, or if they’re generalized across all systems.

vCenter Improvements

vCenter now includes more storage information:

• Each VM and ESX in the inventory has a tab showing storage information and allowing users to set alarms on storage use – setting capacity alarms becomes extremely important when thin provisioning is used!
• vCenter inventory has a view showing datastore details
• There’s also a nice storage topology map

Data Protection APIs (Updated)

VMware also enhanced the APIs for consolidated backup (VCB) into “vStorage Data Protection”. Available only with Advanced or Enterprise licenses, these APIs allow enterprise backup vendors to develop specific integration with VMware without VCB in the middle.  All versions of ESX include this vStorage API and boast VCB support. Standard and Essentials licenses do not include vCenter Data Recovery, a standalone disk-to-disk backup capability for virtual machines.

Conclusion

vSphere is loaded with storage improvements, though many seem like incremental updates rather than new features. Admins will welcome thin provisioning support, and the full integration of Storage VMotion is certainly welcome, but I think the changes to vCenter will be most noticeable. I’ll be looking into EMC’s PowerPath/VE and the amazing I/O improvements as we move forward and learn more about the next ESX!

Duncan Epping posted much more vSphere Linkage on his Yellow Bricks blog if you’re interested in non-storage features. I also suggest reading Chris Evans’ outline of vSphere storage changes.

© sfoskett for Stephen Foskett, Pack Rat, 2009. | Storage Changes in the VMware vSphere 4 Family
This post was categorized as Enterprise storage, Gestalt IT, Virtual Storage. Each of my categories has its own feed if you'd like to filter out or focus on posts like this.

Hopefully, VMware's three pillars (vCloud, vClient, and VDC-OS) are a little more solid (not to mention closer) than the Three Pillars of Creation in the Eagle Nebula

VMware packed a lot into their 2008 VMworld conference, including an outline of their “three pillars” strategy, focused on vClient, vCloud, and something they are calling the Virtual Datacenter Operating System. While it is debatable if this last item really is an operating system, it’s certainly a major strategic change in messaging.

VDC-OS is divided into four “vServices” (Management, Cloud, Application, and Infrastructure), and one core Infrastructure vService is vStorage. Since my focus is enterprise storage, I thought I would take a moment to examine the current and future status of vStorage.

EMC’s Chad Sakac has taken up the challenge of communicating vStorage to the world, in a post to his blog, a pair of YouTube videos (multipathing, I/O dedupe), and (apparently) a session or two at VMworld. But I’m not sure it’s really entirely clear just what vStorage is and what this means to existing and future VMware storage developments. So let’s dive in and take a look.

vStorage = Storage vService for VMware Infrastructure

Let’s get one thing out of the way immediately: VDC-OS is not a new product – it’s a framework to organize VMware’s existing and future datacenter-targeted products like ESX. The company is sweeping away the current hodgepodge of server product elements and placing them all into a more-organized structure called VDC-OS.

As such, the whole thing is not fully baked at present – there are lots of missing elements, and these point to future products from VMware and others. I applaud the organization, and feel that this is the first really viable next-generation datacenter vision that I have seen. It accurately reflects the current reality of the corporate data center and includes a migration path to take it to a compelling new level.

VMware has a realistic approach to bringing current datacenter elements into the future

As we can see in VMware’s diagram (above), the Virtual Datacenter OS is made up of VMware Infrastructure, with application vServices resting on infrastructure vServices or the cloud. This last bit is the fundamental breakthrough that makes VDC-OS more than just slideware – if it works, applications (virtual appliances) can transparently move from local infrastructure to cloud infrastructure owned and operated by others. It’s transformative, and if they pull it off, this could usher in a new datacenter world.

vStorage is one of the core infrastructure services, along with vCompute and vNetwork. Although it’s not entirely clear at this point, vStorage presumably includes all existing VMware storage technologies as well as the new APIs for multipathing and I/O deduplication highlighted at the show. I envision a future in which vStorage is a set of APIs for everything from I/O to device management, and VMware even includes virtual storage appliances in this umbrella.

vStorage: What’s In It?

At the very least, vStorage includes the following:

• VMFS for shared storage
• Thin Provisioning support in VMware Infrastructure is apparently coming in 2009, but is also apparently incompatible with fault tolerance.
• Linked Clones is another desktop technology coming to VI 2009.
• The Site Recovery Manager API has also become part of vStorage, though this isn’t getting much press.
• VMware Consolidated Backup (VCB) will also apparently be a vStorage API.
• The existing snapshot API will also presumably included.
• The new API for Multipathing covers the old generic native multipathing (NMP) from ESX as well as EMC’s most excellent PowerPath. The latter is presumably an extra-cost option that enables lots of niftiness, as demonstrated by Chad in this video.
• Another new API claims to deduplicate I/O, reducing traffic for certain supported disk operations, as demonstrated in Chad’s second video.

What is in and what is out is still kind of up in the air. But you can see that vStorage includes most of our old favorites (VMFS, SRM, VCB), some desktop elements (thin volumes, linked clones), and some new surprises (PowerPath, I/O dedupe). There is enough meat here to separate this from traditional slideware: VDC-OS has legs!

© sfoskett for Stephen Foskett, Pack Rat, 2008. | What is VMware VDC-OS vStorage?
This post was categorized as Enterprise storage, Virtual Storage. Each of my categories has its own feed if you'd like to filter out or focus on posts like this.