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I have a Redhat7.3 machine acting as a server with 1GB of memory.
Today it is automatically rebooting about 15min after starting up the
server each time? My sites have really started to get a lot of hits and
I am wondering if maybe running low on memory could result in the
system to automatically reboot? It is into the swap space now but it
has been for awhile without a hitch?
UPDATE: Now it is just rebooting on its own without even starting up
Did you make any changes to the RAM? Like fancypiper stated, this sounds like a memory problem. Are all of your memory sticks the same speed (eg, PC2700 or whatever) or do you have a mixed bag? If it's mixed, that could be the source of the problem, and the reboots are happening because your memory is getting into an inconsistent state.
Obviously, this could be caused by a power problem too - did the server get plugged into a socket that's controlled by a wall switch, and people come in and turn the lights off/on? Admittedly that would be pretty far fetched but hey, I've seen stranger things -- J.W.
For mysterious reboots, I always suspect RAM unless I personally have run memtest86 in the box it is installed in through the full spectrum of tests and it fully passess one full run of the tests. If time permits, I run several passes.
tail -f /var/log/messages and see what is happening at the time.
top may give some hints. Use the m key to turn on/off memory display
Last edited by fancypiper; 03-22-2004 at 02:40 PM.
Assuming your ram is the same speed and it passed the tests, your system may have been hacked, but I wouldn't know. Anyway, it never hurts to run a virus scanner(I like ClamAV even though a recursive scan takes forever).
My web applications are all java based and I have an Oracle9i db
running as well. Java takes up 60% of the memory and Oracle takes
up about 25% with the rest going to system resources. The funny
thing to me is it worked fine for the longest time even with it going
into the swap space.
Maybe now that my sites getting alot more hits it is going to far into
the swap space and causing the reboot? Aside from maybe being
comprimised (which I am doubting but not ruling out, system is behind
a router with an NAT firewall) could running out of memory cause the
system to suddenly reboot?
Here is something that I find interesting...the system boots up fine
and I start up the web server and the db. Memory is at 53% initially
and then slowly grows to 98% and starts creeping into the swap space?
Memory is not being released and I think the culprit is my java based
web applications seeing how they use the most memory when I check
memory usage with the system monitor...
The consistent increase in the amount of used memory definitely could be due to memory leaks in your apps. As you already indicated, if memory isn't being released correctly, eventually your system will start to become unstable. How to investigate and correct a memory leak is not something that I know how to do, but perhaps others here could suggest a few tips.
The good news seems to be that your system appears to be intact, it's just that your apps are causing instability. If your system is rebooting every 15 or 20 minutes, then I would expect that whatever memory leaks you've got would have to be pretty major, and therefore easily found. Good luck with it -- J.W.