swap space usage

[Robert Gravsjö]

Hi,

I'm seeing something strange on one of our servers. The swap space usage 
keeps growing alarmingly. We've run the server with 2GB swap for over a 
year and everything seems fine. A couple of weeks ago we saw the swap 
space was running out, which was strange, so we started by adding 
another 1GB swap space and then another 1G later on since the first 
addition also got used up.
I belive I can swapoff everything and then swapon the original swap 
space to reclaim the space (or just do a reboot) to fix things. The 
thing is, I really need to know what's causing this.
Has anyone seen this before? Any idea of what's causing it? Is it 
possible to track what process is swapping out? Using ps, iostat, vmstat 
and /proc/meminfo and /proc/stat doesnt give enough information (or I'm 
missing it).

Regards,
Roppert