I have a RHEL v5 Server (it lives as a VM) that runs backups for an Oracle database and we seem to have resource problems with it. If we reboot, it seems to run ok, however over time the performance degrades and we are not sure why.

I've taken the server down, gave it more CPU from 4 to 6 and more RAM from 16 to 24 GB, and now I want to set a performance baseline.

I'm currently using iostat, vmstat and mstat and writing them to a file on the hour for 24 hours straight.

I'm wondering what others have done to prepare a performance baseline for a Linux server?

thanks

You don't appear to have a performance issue, it's more a break/fix problem
You have to figure out why your instance growing on the nodes (to the extent it's problematic) and what's taking up all the storage.
After you resolve those two problems can start tuning your instance for maximum performance.