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Technical white paper | HP Enterprise Virtual Array Storage and VMware vSphere 4.x and 5.x configuration best practices
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If required, set the value to 60 using one of the following commands:
echo 60 > /sys/bus/scsi/devices/W:X:Y:Z
or
echo 60 | cat /sys/block/sdX/device/timeout
where W:X:Y:Z or sdX is the desired device.
No reboot is required for these changes to take effect.
Appendix C: Balancing I/O throughput between controllers
The example described here is based on an environment (shown in Figure C-1) with balanced Vdisk access but imbalanced
I/O access. The appendix explores the steps taken to balance I/O access.
Figure C-1. Sample vSphere 4.x/5.x environment featuring an HP 8100 Enterprise Virtual Array with two four-port HSV210 controllers
Vdisks are balanced, as recommended in this document, with two Vdisks owned by Controller 1 and three by Controller 2;
however, you must also ensure that I/Os to the controllers are balanced. Begin by using the EVAperf utility to monitor
performance statistics for the EVA array.
Run the following command:
evaperf hps –sz <array_name> –cont X –dur Y
where X is the refresh rate (in seconds) for statistics and Y is the length of time (in seconds) over which statistics are
captured.
Figure C-2 provides sample statistics.
Note
The statics shown in Figure C-2 are not representative of actual EVA performance and can only be used in the context of the
example provided in this appendix, which is intended to illustrate the benefits of round robin I/O path policy and ALUA-
compliance rather than presenting actual performance.