I have a home fileserver running Ubuntu minimal 12.04. It has 6 spinning hard drives of data and the system is installed on a USB flash drive. The idea is to have the drives always spun down unless they are being used but have the system always up. (I also use it for other things that do not involve the disks).

I use hdparm to spin down the drives after an hour of inactivity. This works well (i.e., they spend almost all their time spun down and only spin up when individually needed...they are not in RAID). I also use cpufreq to scale down processor speed when not in use.

However, if I leave the system for a day and then connect to it through windows sharing, ssh, or apache I have a long delay and then all 6 hard drives spin up. I suspect that what is happening is that the machine is entering a suspend or hibernate state and when it wakes up it spins up all the drives. This happens frequently and is resulting in my drives spinning up and down a lot--even those drives that are almost never used (one of them is for backups only, for example).

I would like to disable suspend and hibernate without disabling hdparm or cpufreq. It has to be done in a file or from the command line because the box doesn't have X windows or even a screen. There seem to be a ton of different acpi configuration files around but I'm not sure which one governs this behavior.

Any ideas?