On Thu 10 Nov 2022, at 11:36, Gareth Evans <donotspam@fastmail.fm> wrote:
[...]
This assumes the identification of the driver in [3] (below) is
anything to go by.
I meant [1] not [3].
Also potentially of interest:
"Queue depth
The queue depth is a number between 1 and ~128 that shows how many I/O requests are queued (in-flight) on average. Having a queue is beneficial as the requests in the queue can be submitted to the storage subsystem in an optimised manner and often in parallel. A queue improves performance at the cost of latency.
If you have some kind of storage performance monitoring solution in place, a high queue depth could be an indication that the storage subsystem cannot handle the workload. You may also observe higher than normal latency figures. As long as latency figures are still within tolerable limits, there may be no problem."
https://louwrentius.com/understanding-storage-performance-iops-and-latency.html
See
$ cat /sys/block/sdX/device/queue_depth