What and why is my swap space used under linux

view story

http://serverfault.com – on my linux system I get these stats from top: Tasks: 155 total, 1 running, 153 sleeping, 0 stopped, 1 zombie Cpu(s): 1.5%us, 0.3%sy, 0.0%ni, 97.4%id, 0.7%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 8177180k total, 2025504k used, 6151676k free, 44176k buffers Swap: 7999996k total, 495300k used, 7504696k free, 637612k cached There it shows me that my system is using 495Mb of swap. Why is this so? 6Gigs of ram are free. And if I would disable swap entirely the system would also work. Any explanation what the number really shows or who is swapping? (HowTos)