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.