The main server at my company has recently been having a lot of downtime. For reasons that neither I nor the other admins can determine, it has random (VERY sudden) explosions in memory. It becomes unresponsive because it exhausts all the memory, and then we have to reboot it. Very annoying. It's a Debian system, we haven't upgraded to Squeeze or anything, it's been perfectly stable for a long time.
The problem is that the logs are totally useless. They don't seem to indicate that anything is going wrong. I'm guessing that some process is buggy and hogging all of the memory, but I have NO way of proving that at the moment. Remote logging is no help, because it's not complaining about anything -- it thinks everything is peachy.
So my question is: how would you approach this problem? Any insight is appreciated. Thanks.