Over the past months, I had 2 external HDDs forming a RAID 1 (managed via mdadm) attached to my Raspberry Pi and until 2 days ago was under the impression that the HDDs are spun down most of the time, only rotating when they are in use and shortly afterwards.
One of the external HDDs can be influenced on its spin-down timeout via its device settings, the other one can't.
The last 2 days, almost all the time one of the HDDs (not always the same one) is spun up. I suspect that somehow reads happen which is weird because after I killed the owncloud client I was using, nothing should be using the RAID if I don't access it via SSH.
iotop provides my with the names of a whole bunch of processes but to me it looks like those are system processes which merely operate on the SD card. But because there are so many, I might very well overlook the important entry / entries. I want to ignore all those which mere access the SD card so I can focus on those which access the RAID.
How can I find out what process is accessing the RAID (
/dev/md1) or my HDDs (