HDD in idle system stays active

Question

When having Ubuntu 11.10 idle, hard-disk is still doing "something" periodically for a very small time (I have 8GB RAM). I can hear the seeks every few seconds (iostat tells something like 20kB/s).

What process could cause that? I thought that's a Windows issue only.

Answer 1

Use iotop to look at what processes are doing I/O.

Answer 2

You need to put the computer into power save mode:

sudo pm-powersave true

Less frequent writes to the disk means if you crash you can lose more work though.