What’s different about storage for virtual desktops? — Data-Driven Blog by John Webster

By John Webster, Tuesday, February 14th 2012

Categories: Analyst Blogs

Tags: SSD, VDI, VDI storage, Virtualization,

It is often said that data center-level server virtualization projects created a renewed demand for networked storage, both NAS and SAN.

If that’s true, then efforts to virtualize desktops–aka virtual desktop infrastructure (VDI) projects–will create renewed demand for high-performance storage, both network-attached storage (NAS) and storage area network (SAN).

Storage performance is a major determinant in successful deployments of VDI. Why? VDI is a storage input/output-intensive environment.

When you lift the hood to find out what’s going on inside a disk array that’s supporting virtual desktops, you see the following:

The typical virtual desktop running Windows apps is moving almost 1MB of data per second with an access rate of approximately 10 I/O’s per second (averaging 100KB per I/O).

Characterizing a rule of thumb for the I/O profile for VDI can be very difficult. VDI generates data blocks that vary dramatically in size, from 512 bytes to 2MB. Read/write ratios can vary from 30/70 to 60/40. Also, accesses are almost completely random.

All of the which creates a storage environment where both performance and management simplicity are appreciated. Some of the attributes of modern storage architecture will be in demand as a result. These include:

  • Solid state disk (SSD) for performance, implemented within the storage array level as either “tier zero” in a tiered storage array or as cache.
  • The ability to generate thousands of writable snapshot copies to quickly provision desktop images.
  • Thin provisioning to allocate disk capacity on demand rather than pre-allocating capacity.
  • Automated provisioning assistance.

VDI is quickly rising in popularity within the education, health care, and government segments. Others will join during 2012. Getting the storage environment right will be a critical consideration for all however as IT administrators across the business and organizational spectrum will witness the same basic storage requirements. Therefore, having some way to run a reliable test phase before a major production VDI deployment is an absolute requirement. Modern storage architectures that support the attributes outlined above will also be highly sought-after.

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