
EMC Infrastructure for Virtual Desktops Enabled by EMC VNX, VMware vSphere 4.1,
VMware View 4.5, and VMware View Composer 2.5
Table 7 provides a summary of the memory required per host.
Table 7. Required memory per host
RAM/host min
required
(Complete
Cluster)
RAM / host min
required (Cluster
with one node
down)
RAM/ host used
on this solution
We used 1,536 GB in total for hosting 2,000 virtual desktops. In a typical case, 1.5 GB per
desktop will not be available and will be using 2 GB and it would require 4,000 GB in total.
Still, virtual desktops can provide better bootup time compared to traditional PCs.
Network
Based on the workload, we found one virtual machine requires approximately 18 Mb/s. So, a
100 Mb/s card can support five to six virtual machines per NIC, a 1 Gig NIC can support 50-60
virtual machine per NIC and a 10 Gig NIC can support 500-600 virtual machines per NIC. The
Converged Network Adapter (CNA) running at 50 percent bandwidth can support 250-300
virtual machines per CNA.
Note: This is just a rough estimate and we must always watch for the network load and look
for the percent packet drops. If the value is high, check the network configuration and it might
be the time to consider adding another NIC. In our solution, we used two CNAs per host to
provide fault tolerance. For 2,000 virtual desktops, we used 2×8×3= 48 NICs. In a traditional
desktop scenario, 2,000 desktops require 2,000 network interface cards.
Storage
The number of spindles required for hosting 2,000 user desktops is calculated using both the
IOPS requirement and the capacity needed. Based on the workload, we observed 8.3 IOPS
per virtual desktop on average. The maximum and 95
th
percentile is based on the time
interval of the data. The sizing on the average IOPS can yield good performance for the virtual
desktops operating in a steady state. However, this leaves insufficient headroom in the array
to absorb high I/O peaks. To combat the issue of I/O storms, there should be two to three
times the average to absorb that load. Table 8 details the IOPS requirement and Table 9
describes the disks needed by various RAID levels to meet that IOPS.
Table 8. IOPS requirement and disks needed (multiple RAID scenarios)
Number of Windows 7 desktops
IOPS per Windows 7 virtual machines
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