[root@linode ~]# free -m
             total       used       free     shared    buffers     cached
Mem:           498        442         56          0         25        119
-/+ buffers/cache:        297        200
Swap:          511        125        386

I am on 512 linode hosting around 30 websites and email domains. Average bandwdith usage is 1GB per day.

Can someone tell me why swap space is used when free and cached memory is available?


Is amavisd being used for all incoming/outgoing emails?


Thanks
Richard

There is a Linux kernel tuning parameter for swapping, amusingly and aptly name "swappiness", that is discussed here:

http://kerneltrap.org/node/3000

and here:

https://help.ubuntu.com/community/SwapFaq

I have swappiness on my linode set to 100, which works well for me. Even with the parameter set to zero, some swapping will still occur.

James

The logic is that unused or seldom-used RAM is wasted RAM. The kernel will swap out stuff that isn't actively used, and use the freed RAM for caching and other useful things.

There should be a net performance gain, unless you have a strange usage pattern, in which case adjusting swappiness can help.