Sunday, February 7, 2010

Overcoming the VM I/O Blender?

Last week I was invited to come out and visit with a new company in

the virtualization space called Virsto Software. Virsto is based out

of Sunnyvale, CA and they have developed a new software solution

that will solve a lot of the inefficiencies known to virtualization.


When considering virtualization in the data center a couple of goals

that come to mind are reducing physical footprint, gaining higher CPU

utilization and reduced provisioning time. Hyper-V has provided

affordable options to address these requirements, but limiting factors

still exist. One of the biggest problems that we are faced with as we

start loading up VM's on the host is the I/O blender effect. When you

have a single OS to disk relationship the I/O is smooth, but as you

add additional VM's the hypervizor has to manage all these different

I/O loads and this causes the streams to not flow smoothly anymore and degrades I/O performance. Then there is VM Snapshots that so severely degrade I/O that most data centers have a policy against using them in production.


Virsto's new solution has answers to all these problems and more.

Their solution is also vendor-agnostic, so its works with any storage

solution. Virsto has integrated their software into the native Hyper-V

Manager snap-in, so the footprint is very small on the Host. This

integration allows an administrator to manage their VM deployment,

Snapshots, golden VHD's and Clones all from a single pane of glass.

They have even built their solution to be cluster aware giving data

centers options to improve performance and managements of all their Hyper-V environments.


To address the I/O blender effect they have incorporated a new file

structure that presents Hyper-V disk files as native VHD's to the VM,

but are stored on disk in a format they call vDisk. This newly

developed file structure allows I/O to remain smooth as VM density is

increased and regains a lot of the lost I/O performance from VM's hosted on native file systems. In my own testing I was able to show I/O performance gains between 20-30% over native Microsoft VHD's when benchmarking 1 -25 VM's. But, the biggest improvement was post snapshot with I/O performance with Virsto being as great as a 50% improvement in cases up to 25 VM's. This results in greater VM density and greater storage savings.


Virsto has also addressed concerns with storage sprawl and cloning. In most production environments we work with a number of golden fixed VHD's, many of which may not be used and take up valuable space. Provisioning is time consuming since its based on a file copy process. Virsto implements fixed VHD's same as Hyper-V, but the Virsto provisioning solution commits only the required disk space without having to fully expand the VHD, saving valuable disk space. This same concept applies to provisioning clones from Virsto's built-in cloning feature. When compared to Hyper-V native provisioning of a 70GB fixed VHD this process could take between 5-15 minutes, but in every cloning test case I performed I was able to create the clone and have the VHD ready for boot in just seconds, a tremendous time savings.


Given the potential for drastic storage savings and provisioning improvements, I believe Virsto is a solution that Hyper-V administrators will be adding to their host deployment checklist.


If you would like to learn more about Virsto Software, then check out the link below.


http://www.virsto.com/

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