VSAN-Troubleshooting-Reference-Manual

Diagnostics and Troubleshooting Reference Manual – Virtual SAN
Checking your storage I/O controller queue depth
A good practice is, from time to time, to re-check that everything is behaving
correctly from an ESXi perspective. One of the most critical items related to storage
is the queue depth, and we have seen the negative impact that small queue depths
can have on Virtual SAN performance. If, after upgrading a storage controller’s
firmware, verify that it has not reduced the queue depth in any significant way (this
is an issue we have seen in the past with new controller firmware versions).
Esxtop for controller queue depth
The easiest way to check the controller queue depth is to use the ESXi command
esxtop. When esxtop is launched, hit the (d) key to switch to disk view. Next hit the
(f) key to add more fields and the field that you need to add is “D” for Queue Stats.
When this is enabled, hit return to revert to the disk view screen and now a new
column is display, AQLEN that is short for “adapter queue length”. Here is a sample
output of one such configuration:
Note this will have to be repeated on all ESXi hosts in the cluster. At the time of
writing this manual, VMware is currently only supporting adapters with a queue
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