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Sizing and Best Practices for Deploying VMware View 4.5
on VMware vSphere 4.1 with Dell EqualLogic Storage
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5.4 Performance Considerations
In general, the design considerations specific to VDI performance focus on supporting the workloads
generated by a typical desktop session lifecycle (boot, login, work activities and logoff). Quantifying
the average I/O workload generated by the user profile (task worker, knowledge worker etc.) is
important for performance and sizing considerations. The storage platform used in a VDI deployment
should be able to sustain the maximum IOPS these workloads create within acceptable latency limits.
Login storm is a worst case I/O workload pattern, especially for non-persistent desktops. In our testing
we confirmed that login storm periods generated much higher storage system performance demands
than after all logins were complete and users were in a steady state pattern of application usage. When
using persistent desktops, the login storm effect can be negligible (except for the first time login of all
desktops).
From our tests we measured I/O patterns for the task worker user profile during the simulated login
storm period as follows:
• Login Storm (non-persistent desktops):
o 50/50 read/write ratio
o 36KB read and 10KB write block size
o 8 - 13 IOPS per desktop
• Steady State (persistent and non-persistent desktops)
o 25/75 read/write ratio
o 18KB read and 10KB write block size
o 3 - 4 IOPS per desktop (from application events in the task worker user profile)
5.4.1 When to use the EqualLogic PS6000XVS
The I/O performance measured at the maximum load (presented in Section 4.2) indicates that the
PS6000XVS could host significantly more desktop VM images and still stay within I/O latency limits.
You should consider using the EqualLogic PS6000XVS for VDI environments that will have high IOPS
requirements (larger VDI environments running non-persistent desktops). You should also consider
using the PS6000XVS in persistent desktop environments that will need to support a large number of
users generating heavy application I/O. In general, you should consider using the PS6000XVS in any
environment where the I/O performance boost provided by automatic movement of stored data
between the SSD and SAS tiers will help to meet workload performance requirements.
5.4.2 When to use the EqualLogic PS6000XV
The test results in Section 4 show that the PS6000XV was able to host 390 non-persistent task worker
profile desktops while staying within I/O latency limits. Based on this result we recommend the
PS6000XV for small VDI environments running non-persistent desktops with moderate I/O
performance requirements. The test results in Section 4 also show that the PS6000XV was able to host
780 persistent task worker profile desktops while staying within I/O latency limits. Thus the PS6000XV
may also be a good fit for larger VDI environments where login storm effects are not a concern.