hdparm -C always shows standby

Hi peeps, not sure if I’m misunderstanding how hdparm is supposed to work or if this is a bug.

I got an old laptop hard disk plugged into a hd enclosure, which is plugged into my rpi2b via usb.

When I do “hdparm -C /dev/sda” the result is always “standby” even when the drive is clearly in use.

The standby does seem to work properly because I can hear the drive go completely silent after several minutes of non use, and I can hear it power up when I try to access it. It’s just the hdparm -C command which doesn’t seem to work. Not super important, but I’d still like to understand why it’s nor working if possible. Any ideas?

Basically not all drives support hdparm vice versa fully. Same e.g. for APM (Advanced Power Management) which can be configured via hdparm but modern drives do mostly not support it anymore.

Btw I can verify the same for all my external drives on my RPi2. Probably the way those drives are attached via USB breaks correct state estimation, not sure.