After installing the jails plugin together with bacula-sd and Firefly the disks in my Freenas box wouldn’t spin down. I first thought of Firefly doing something strange but that wasn’t the case.
I then disabled the complete jails plugin and the disk would spin down again after ten minutes (what I configured in the admin interface).
I came upon a bug about standby not working when the jails plugin was enabled. I followed the directions there and symlinked the tmp and log directory in the jail to a memdisk fs. I rebooted the machine but the disks still wouldn’t spin down.
I broadened my search and decided to also include freebsd resources. I found out that it probably had something to do with a cron job. So I did some testing and I came up with two cron jobs that kept waking the disks:
I disabled both of the services and now the disks spin down again!
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ssh freenas jexec 1 /bin/tcsh crontab -e
I then just commented out the save-entropy and atrun cron jobs.