Error 503 service unavailable while ram is free

[Tunis0101]

CWP is reporting that ram+cache is full while ram is almost at 25% but I'm still facing error 503 on peak visits time.

will this be fixed If I delete varnish?

[Tunis0101]

Should I make varnich cache files on the disk?
edit: I just read that you can store some files on RAM (css, etc..) and the rest on disk.
can someone explain how to do that on cwp?

[Sandeep]

it can be open file limit is set to low value for an account.

by default varnish uses malloc which is ram cache engine.