Desktop virtualization is a rapidly growing segment of the IT industry. According to a November 2011 report, IDC expects the spending growth of virtual desktop infrastructure (VDI) will exceed the growth of the overall IT market over the next five years.

We find evidence of this growing VDI adoption among Dell EqualLogic customers. In our 2011 survey, 25% of our customers reported that they already have VDI deployed in the enterprise or in PoC; additional 13% intended to deploy VDI by 2013.

Citrix XenDesktop is one of the leading VDI solutions in the market. We recently conducted a series of VDI tests to develop best practices and sizing guidelines for a Citrix XenDesktop based VDI solution deployed on Dell EqualLogic storage. The primary objectives of our testing were:

• Determine how many virtual desktops can be deployed using a single EqualLogic PS6010XVS array – with its mix of SSD and 15K SAS drives within the same chassis – for task worker profiles.

• Determine the performance impact on the storage array during peak I/O activity such as boot and login storms.

• Determine how to scale the number of virtual desktops by adding additional storage array members.

We found that a single PS6010XVS array was able to host 630 virtual desktops supporting task worker workloads. Two arrays were able to support 1270 such desktops. The details of the findings are available in this report.

While you get the details from the report, it is worth highlighting boot storm results here in the blog.

Boot storms create the highest load on the storage infrastructure in a VDI environment. Unless the storage platform is designed just right, a boot storm can easily bring the entire VDI infrastructure to its knees. Additionally, it is very important to bring all the virtual desktops up and running as quickly as possible.

To test the hybrid PS6010XVS array’s capabilities, we restarted all 1270 virtual desktops simultaneously in the two-array configuration. The net results:

All 1270 desktops were booted within 12 minutes!!!

The peak IOPS when 1270 virtual desktops were booted was around 15000. The average latency on both storage arrays was less than 10 ms and the storage arrays were able to handle this I/O burst with no significant increase to the latency. See Figure 1 below.

Another point worth noting from Figure 1: The read-write mix for the peak IOPS was approximately 10%:90% (common for Citrix Provisioning Server based XenDesktop solutions). We, the storage specialists, all know the IOPS capabilities go down dramatically as the write percentage in the workload goes up. Delivering 15000 IOPS under 10 ms latency with 90% write workload by two PS6010XVS arrays was truly remarkable.

Figure 1: EqualLogic array performance for the 1270 virtual desktop boot storm

Get all the details from the paper here.