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BP1018 Sizing and Best Practices for Citrix XenDesktop with Dell EqualLogic Storage 24
Figure 10 IOPS monitored using ‘Live View’ feature of SAN HQ during login storm – 630 VMs
The storage array disk latency never went beyond 5 to 6 ms even at the peak I/O during the login
storm. We observed an increase in CPU and network resource utilization at peak login, but it was well
within the acceptable limits.
5.4.3 Hypervisor layer: ESXi host performance
During the test, we measured CPU, memory, network, and disk performance on all ESXi servers
hosting the virtual desktops.
The key observations on the ESXi servers were:
• CPU utilization did not reach more than 95% at any point in time, ensuring sufficient resources
for all of the virtual desktops.
• The average disk latency of all disks on the ESXi server was less than 2 ms.
• There was no memory ballooning and the peak memory utilization was less than 50%.
• Network design is very critical because provisioning servers will stream the master VM image
over the network to all virtual desktops. The peak network utilization on any ESXi servers was
not more than 25 to 30%.
5.4.4 Citrix infrastructure layer: PVS and DDC performance
We monitored the resource utilization on the ESXi servers hosting the XenDesktop infrastructure VMs
while running the test. Since the two provisioning servers and DDCs were load balanced, the
performance on each ESXi server was similar.
CPU utilization:
PVS and DDC servers had two virtual CPUs and 16 GB of memory allocated. We observed slightly
higher CPU utilization (around 5%) during the login storm due to streaming activity. After that, the
utilization remained consistently below 2% to 3%.
The slightly higher CPU utilization during the initial stages was caused by various factors such as: