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VMware shops greet Virsto arrival with caution

Though VMware acquired storage I/O acceleration software maker Virsto Software, some IT pros question the potential benefits of adding another layer.

VMware customers have mixed opinions as to whether storage I/O acceleration software the company acquired recently will offer their enterprises any true value.

VMware snapped up Virsto Software for an undisclosed sum this week. Virsto's storage I/O acceleration product will continue to be supported in standalone virtual-appliance form and will be integrated with VMware's products, VMware said in a blog post. The acquisition is expected to close this quarter.

The Virsto product is not a storage virtualization technology per se, as it sits a layer above underlying storage systems, which can also be virtualized. But with two layers of abstraction -- the Virtual Machine File System (VMFS) and VMware Virtual Disk File -- already sitting between raw disk and guest VMs, some IT pros are flummoxed by the arrival of another layer. 

"The question is, does what you gain more than offset the complications to your life in terms of support overhead, cost and potential to go horribly, horribly wrong some Saturday evening and corrupt all your data?" said Bob Plankers, virtualization architect for a major Midwestern university. "Maybe? Maybe not."

Some feel the technology is worth it because of ever-expanding storage costs.

"Most people agree that most companies are realizing only a 33% utilization rate on their SANs [storage area networks]," said Chris Harney, an independent consultant who specializes in virtualization. "So, if you pay $50,000 for 36 TB of raw storage, you are really paying $50,000 for 12 TB of usable storage."

Virsto's software intercepts I/O from guest machines and creates a sequential log file. This aligns random writes to disk into a sequential pattern that better suits storage I/O to improve performance. When data is destaged to disk, the log optimizes data layout and deduplicates redundant blocks of data to optimize storage capacity.

Virsto also inserts pointers into its sequential log to create snapshots and clones, and claims it's able to do a greater number of snapshots on this sequential stream of data with a performance that's an order-of-magnitude faster than that of traditional snapshot mechanisms.

Virsto's software better suits storage I/O to improve performance.

VMware's storage future

When VMware detailed its software-defined data center plans, it was only a matter of time before a storage-related product was added to the mix, said Christian Mohn, a senior infrastructure consultant at EVRY Consulting in Bergen, Norway. 

"The Nicira acquisition took care of the networking part; now Virsto is set to be the storage bits that were missing at the time," he said.

For others, products that hook into the hypervisor are not worth the risks.

"While it does save money by using more of the existing resources, and it can make things easier for the end users, it does not make it easier for the IT folks," said Wayne Gateman, an area coordinator of virtualization at a large medical distribution and software company. 

"When you set up anything with that many moving parts, you will, when it works, have a great front end. However, when issues arise, you end up in a troubleshooting, finger-pointing hell."

Virsto's product initially supported Microsoft's Hyper-V. It added support for VMware products just last year. While some IT pros wonder if support for multiple hypervisors will continue under VMware, analysts said they believe that retaining that support would bolster VMware's pledge to support multiple hypervisors with its management tools.

"[VMware needs] to do more than give lip service about extending their tools to support multiple hypervisors," said Greg Schulz, founder and senior adviser for the Server and StorageIO Group.

Beth Pariseau is a senior news writer for and Write to her at or follow @PariseauTT on Twitter.

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Do you look forward to seeing Virsto's IP added to vSphere?
VMFS is suboptimal - will be great once they swap it out and use Virsto's data services instead. Snapshots that have no performance penalty? sign me up.
The "...finger pointing hell" comment from one of your interviews says it all for me. VMWare is already so layered adding another layer of complexity is not something I look forward to.
While VMware quality PLUMMETS they decide to buy virsto to add another layer in the storage stack? What? Who's running things at vmware these days? The fact that VMware felt they needed to buy virsto shows just how bad things are and how vmw have lost their way. This should be an esx storage optimization not an acquisition. Debugging this should be a nightmare. no thanks. Congratulations VMware you look clueless these days.
Too much comlications ...
if well integrated it will greatly help in reducing storage cost + improving storage performance, looks like a good deal to me imho...
doesn't another two storage startups have the same idea? Tintri & Nimble storage?
I like the concept. May take a couple,of releases to get it right.
ordering queries before they go to storage will cut down on random I/O which should improve overall performance. This would seem to be an area that VMware would pursue just to avoid having the nature of virtualization pessimize storage the way it does.
Higher end performance from lower tiered disk, less storage usage and managed at VM level not storage level.
Tintri and Nimble need a storage appliance to do their optimization, Virsto runs right in the hypervisor with exact VMware workflows, very simple to manage and not another hardware appliance to worry about.
There is always "finger pointing from hell" you think this is going to make any worse? Ha-ha...
Expect much better storage I/O and efficient use of available storage capacity. Cost of Virsto SW is an issue.