Thank you for your reply.
We do not experiment any performance issues. We are just trying to better understand how the MSA is working. By disabling the scrub jobs, we are [pretty] sure the MSA is just handle I/O coming from our OpenVMS Server (attached to 2 SAN Switches).
Looking at the statistics provided by the MSA and compared it with statistics provided by OpenVMS is our objective (of course at OpenVMS we are looking the physical I/O). During the last 24hours, an average of 25I/Os is done per disk (with a peak to 200 IO/s every 4 hours tied to a backup task) whatever the graph I used (disk or disk-groups) with an average response time of 0,5ms (500µs). But when we are looking the 'queue depth' for the same period, the displayed value is about 5000 Million .
So the question is : where these fgures (queue depgh) come from? It is a calculation?
Concerning scrub jobs, one improvement should be to have a kind of cron table in order to schedule them at a desired datetime. Even if it is a backgroup activity which normally does not impact other IO, for reporting it is better to know when this task is running to eliminate the associated period from our custimized report.
I will ask the customer to open a case about Queue Depth.
Thank you