I am using Debian Jessie on a HP Proliant Microserver Gen8 with two Western Digital Red 3TB. No RAID or anything else. I wanted the HDDs to automatically spin down after two hours. Triggering it manually works fine with both commands
sudo hdparm -Y /dev/sda
sudo hdparm -y /dev/sda
so the output then is
user@NAS:~$ sudo hdparm -C /dev/sda
/dev/sda:
drive state is: standby
But when I use:
sudo hdparm -S 244 /dev/sda
the HDD won't go into any kind of standby mode. Note that sda is not the system drive. I mounted both HDDs via fstab like this:
UUID=xxx /mnt/Stuff ext4 defaults,noatime,nodiratime 0 0
Any idea why this won't work? I also tried 10 seconds and 1 minute. Is there a way to determine if there is any process accessing the partitions on the HDDs? I do use a DLNA Server and Samba, but no access has been made by me during the test, of course.