You can disable AQDA by simply setting both the QFullSampleSize and QFullThreshold back to a value of “0“.
Disabling this feature does not require a reboot.
Important Note: One issue that we have been able to reproduce in our environment (on 6.7U3) is that disabling AQDA may result in the ESXi host setting the Queue Depth to a value of “1”. This means that once you disable AQDA you may notice that your I/O throughput and latency gets worse! If you were to look in ‘esxtop’ you would see that the queue depth (DQLEN) would be reporting a value of “1” rather than the default of (likely) 64 or 32.
In order to resolve this you can either:
- Re-enable AQDA and then disable it again immediately after.
- Reboot the ESXi host
Obviously re-enabling and disabling again is quicker and less impactful to the environment. The only caution to note here is that I don’t know if any other underlying problems are created as a result from that. I personally haven’t noticed any issues, but if you prefer to take the safe route, then a reboot may be best for your environment.
If you decide that AQDA should be used in your environment it is very important that you enable it on ALL hosts within the cluster. If you do not then you could make things even worse during times of congestion.
For more information you can review the following VMware KB:Controlling LUN queue depth throttling in VMware ESX/ESXi (1008113)