On my main system (up-to-date gentoo), I use hd-idle to send my HDDs to standby after a certain amount of time. Disks are SATA HDDs in non-RAID operation - 4xHGST, 1xWDC, 1xSamsung - same behavior for all.
Up to kernel version 5.4.72 this worked perfectly fine. If I use any kernel greater than 5.4.* the disks stay up perpetually. I tried with versions 5.6.4, 5.7.6, 5.8.14, 5.11.6 and 5.12.8. Same for hdparm. I think something is accessing the disks (I checked with a command I cannot recall right now).
To be clear, if I boot with 5.4.72, everything works as expected. If, on the same system without any changes, I boot into a later kernel - no standby.
For context: I use my system as desktop and NAS simultaneously. The disks which are rarely accessed are sent to sleep quickly and the ones accessed more frequently have a longer timeout. Depending on the active/standby state of all disks, I then send the whole system to sleep.
Up to kernel version 5.4.72 this worked perfectly fine. If I use any kernel greater than 5.4.* the disks stay up perpetually. I tried with versions 5.6.4, 5.7.6, 5.8.14, 5.11.6 and 5.12.8. Same for hdparm. I think something is accessing the disks (I checked with a command I cannot recall right now).
To be clear, if I boot with 5.4.72, everything works as expected. If, on the same system without any changes, I boot into a later kernel - no standby.
For context: I use my system as desktop and NAS simultaneously. The disks which are rarely accessed are sent to sleep quickly and the ones accessed more frequently have a longer timeout. Depending on the active/standby state of all disks, I then send the whole system to sleep.