White Papers

BP1018 Sizing and Best Practices for Citrix XenDesktop with Dell EqualLogic Storage 26

Figure 11 Total IOPS at member level – 20% Pre-boot scenario

In this scenario, the time required to login to 630 virtual desktops was almost 100 minutes. In the

100% Pre-Boot scenario it was just 20 to 25 minutes. This is because 80% of the desktops had to be

booted before logon and this resulted in increased logon duration. In this scenario, a user will

experience considerably longer login duration. The read IOPS on storage was low due to streaming of

the disk image from provisioning servers. As seen in Figure 11, the write IOPS constantly varied

between 4000 and 5500 IOPS for more than 40 minutes during boot and login time. This variation in

IOPS was due to the fact that both boot and login operations occurred simultaneously during this

period. The maximum write IOPS observed was similar to the 100% Pre-boot scenario, but it was

sustained for a longer time due to the boot and login happening simultaneously.

The other performance characteristics at the hypervisor layer, Citrix Infrastructure layer, user

experience measures on virtual desktops, and write cache utilization were the same as the

observations captured during 100% Pre-boot test scenario.

5.6 Virtual desktop scaling with two arrays

This test was the same as the 100% Pre-Boot test described in section 5.4. Here we wanted to validate

the scalability of the VDI solution by adding an additional storage array. We added one more

PS6010XVS array to the same pool and also added eight more blade M610 servers to the VMHA ESXi

cluster hosting virtual desktops. In this test, two PS6010XVS arrays with a total of eight volumes each

with 500 GB capacity were used. They were individually mapped to their respective datastores and

presented to the 16 ESXi servers. A single vDisk volume was used to store the base OS disk image

which got streamed to all virtual desktops.

5.6.1 Storage layer: EqualLogic array performance

Figure 12 shows the total IOPS on the EqualLogic pool which consisted of two PS6010XVS arrays in

the same pool. All the users logged into the virtual desktops within 25 minutes. The peak IOPS during