User guide

Technical white paper | HP Enterprise Virtual Array Storage and VMware vSphere 4.x and 5.x configuration best practices
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Monitoring EVA performance in order to balance throughput
ALUA compliance in vSphere 4.x has significantly reduced configuration complexity and given you the ability to quickly
configure a balanced Vdisk environment. However, you should monitor EVA host port performance to ensure that this
configuration is also balanced from the perspective of I/O throughput.
Even though Vdisk access may be well-balanced between the two controllers in a particular configuration, it is possible that
most or all I/O requests are going to Vdisks on just one of these controllers. In this scenario, the resources of one of the
controllers are not being fully utilized. For example, Figure 21 shows an environment where the majority of I/O throughput
is routed through a single controller despite the environment being balanced from the perspective of Vdisk access. Each
port on Controller 2 is processing 300 MB/s of I/O throughput, while ports on Controller 1 are only processing 20 MB/s each.
Figure 21. Unbalanced I/O access in a vSphere 4.x environment
Better balanced throughput could be achieved in this example by moving one or more of the Vdisks on Controller 2 (Vdisk5,
6 or 7) to Controller 1. Simply update the Vdisk controller access preference within Command View EVA to the desired value;
alternatively, if you need to move multiple Vdisks to an alternate controller, you could use SSSU scripting tools.
Within a few minutes of the update, vSphere 4.x will switch the I/O access path of the Vdisk to the new controller, resulting
in better balanced I/O accesses that may, in turn, lead to improved I/O response times.