OS configuration

[Mistoffeles]

Ok, I have Core 2 Quad running 64-bit RHEL 5.3, with 4GB RAM.

This server is going to be completely dedicated to Zimbra, X won't even be installed, all configuration will be done via the Zimbra web interface or through SSH on the command line.

Do I really need twice the system RAM for the Linux swap partition like it says in the installation guide, or will 4GB be enough? To me it seems that a swap file would not even be needed, although Linux requires a minimal one at the very least.

[fcash]

If you want to debug kernel crashes, then you need at least swap==RAM.

Beyond that, you need to think about how many simultaneous connections will be handled, how many web sessions there will be, how many ... etc. Figure out how much RAM that will all take, add 10-20%, and then make sure that RAM+swap covers that number.

Or, if you have several gig of RAM, just create a 1-2 GB swap, and monitor swap usage. If it gets above a couple hundres MB, then you know to add more RAM to the server.

Nowadays, I view swap usage more as a hint for when to add RAM, then as a safety-net for running out of RAM. I've yet to find a server that would burn through RAM faster than our notification software could alert us to an issue.

[Mistoffeles]

I certainly hope the kernel doesn't occupy my entire physical memory In any case, the swap is at least that.

I'm not one to be debugging kernel crashes anyway, what I know of Linux has been on an "as needed on the job" basis. Nothing like jumping in both-feet-first to learn lots of stuff, but still be missing crucial pieces of the puzzle.