Virsto installs as a virtual appliance on each physical machine. It intercepts input-output requests and processes them into a fast log file that can use a solid state drive or rotating magnetic drive in a shared storage area network (SAN). This reverses the 'I/O blender' effect that virtualization imposes on the server, as the log is accessed serially for all virtual machines running on the physical server. The log file is then processed sequentially against the shared storage. This speeds the operation of all virtual machines and reduces the load on the shared storage. This is all done without the expense of adding solid state drives to each server and using caching algorithms, which is the alternate approach to curing the I/O blender effect.
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With Virsto, customers can see cost reductions of about 50% at the storage level, according to the company's claims. The savings are delivered through thin provisioning of virtual desktop images and reduced load on shared storage systems. The thin provisioning of the virtual desktop allows more virtual machines on fewer physical servers, which have typical increases in performance by an order of magnitude. Hundreds of virtual machines can be cloned in a few seconds, easing the management of a large number of virtual desktops. Other storage management features include virtual machine storage self-provisioning, automated storage space reclamation, thin provisioning, and tiering of golden master and user data volumes.
The Virsto XenDesktop implementation provides native support for VMware vSphere 4.1 and 5.0. A beta version of the product is now available. Other Virsto products provide support for server virtualization with both VMware and Hyper-V.
Virsto was co-founded in 2007 by CEO Mark Davis, formerly of Creekpath, CTO Alex Miroshnichenko, formerly of Acronis, and VP of engineering Serge Pashenkov, formerly of PowerFile and Veritas. The company is funded by August Capital, Canaan Partners, InterWest Partners, Southern Cross Venture Partners, and Correlation Ventures for $19 million.
Other vendors who have used the term I/O blender to describe the advantage of their products are Pure Storage with its FlashArray, Dataram with its XceleSAN caching appliance, Xsigo with its I/O Director, and Atlantis Computing with ILIO. Xsigo is thought to have originally coined the term.
Deni Connor is founding analyst for Storage Strategies NOW, an industry analyst firm that focuses on storage, virtualization, and servers. James E. Bagley is senior analyst and business development consultant at the same firm.