I'm not the "high load on linux" expert, but I'll put some things down. Likely you will have to watch this and see if the same behavior happens again.
- Swap is slow, so when you see no (or very little) swap being used, that is a _good_ thing. You want to fully utilize your RAM. If you see swap being used, then you either have too little RAM, or your server is running too much stuff. So from your first post, knowing nothing more, it does not _seem_ like a low-RAM situation.
- watch your load average... from your first posting, a load avg. of 9-10 is too high. Stated simply, your CPU(s) are not keeping up with the work queued up for it. You state a large number of users, but haven't listed what kind/number of CPUs in this machine.
- I find it interesting that the first post listed 324 processes, and the most recent one listed 134. I haven't been running Zimbra enough to know if based on load/# of users, if more processes/threads are spawned or what. I know nothing about openfire.
- You also dont' say anything about disk... what kind, how many, is it RAID, etc. This could also very much be part of the equation.
Keep an eye on it.... but your issue, at face value, does not appear to be lack of RAM.  |