Is swap a bad thing?

I had the same problem some time ago. Moving to a larger Linode worked for me.

James

Gonna hijack this thread.. My memory usage is ~250 mb out of the 512 but it's using 62 MB swap.. is that a bad thing?

swapping out is good, swapping in is bad.

run

vmstat 1

and watch the si and so columns, if there's constant activity, you need to do something.

you should get to know what's normal and what's not, so run it often so when things do become slow or OOM, you'll know what it's meant to look like. That goes for all monitoring tools, like top, etc.

If you're using apache prefork and especially if you're using mod_php, you need to modify maxclients and possible keep-alives to make your server degrade gracefully under a high web load, otherwise with the default settings, your vps will OOM and require a reboot, whereas if you tune apache, your web sites will be very slow to load under a high web load, but your vps will be up and happy, you'll be able to log into it, etc.

I won't go into all the details, you can find guides in the library or on google.

Sorry for the really slow replies. Took a while to get used to these things. I shall keep tabs on that. Thanks!

if you use your swap space. there will be a considerable slowness in your application

@nalanda:

if you use your swap space. there will be a considerable slowness in your application
As chesty said, that's only a problem if you're swapping in a lot. If you swap out a chunk of some daemon that starts on boot and then does nothing ever, it actually helps performance, since it's more useful to use the RAM for the disk cache.

Which is why it's good to have a little bit of swap, but not much. I'd say you should have 1/4th or 1/8th of your RAM as swap, just to give you enough room to take some of that unnecessary stuff out of RAM, but not enough to cause slowdowns.