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Old 03-22-2004, 12:11 PM   #1
defa0009
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Question System automatically rebooting!


Hi,

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
the server!

TIA

Last edited by defa0009; 03-22-2004 at 12:26 PM.
 
Old 03-22-2004, 12:47 PM   #2
fancypiper
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I suspect bad memory if I can't find some suspect in the logs.

Try running MemTest86 and make sure your RAM is OK.
 
Old 03-22-2004, 01:14 PM   #3
J.W.
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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.
 
Old 03-22-2004, 02:25 PM   #4
defa0009
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Memory is ok and both sticks are of the same brand purchased at
the same time.

Power not an issue...computer is in the kitchen plugged into the
120V outlet from the stove which is connected to a 90AMP line so
lots of juice is getting to the computer.


Memory usage is at 98% with 12% of swap being used! I wonder
if this is the problem? I might have to move up to 2GB of memory?
Any more ideas...
 
Old 03-22-2004, 02:35 PM   #5
fancypiper
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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.
 
Old 03-22-2004, 03:52 PM   #6
defa0009
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Now Samba doesn't work! I check the Samba logs and there was a log
called YourRsv100.log? No machine I know! I wonder if I have picked up
a virus?
 
Old 03-22-2004, 04:01 PM   #7
defa0009
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Quote:
Originally posted by defa0009
Now Samba doesn't work! I check the Samba logs and there was a log
called YourRsv100.log? No machine I know! I wonder if I have picked up
a virus?

Disregard this comment...it's working!
 
Old 03-22-2004, 04:04 PM   #8
fancypiper
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Sounds as if you are compromised to me.

# Basic Linux security
Seeing unusual network activity? chkrootkit is a tool to locally check for signs of a rootkit
Linux Questions Security references
Security Help Files
Linux Administrator's Security Guide
Security Focus
Linux Security
Firewalls and Security
 
Old 03-22-2004, 04:19 PM   #9
Brane Ded
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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).
 
Old 03-22-2004, 04:59 PM   #10
MS3FGX
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If you are using 98% of 1 GB of RAM, you have a serious problem. Especially if this is a web server.

I would say it is a virus of some sort. Check "top" to see what is using the most resources, and figure out what it is and where it came from.
 
Old 03-22-2004, 06:02 PM   #11
defa0009
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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?

Thanks again for everybody's input!
 
Old 03-22-2004, 06:26 PM   #12
AutOPSY
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yes.
 
Old 03-23-2004, 09:18 AM   #13
defa0009
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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...
 
Old 03-23-2004, 11:01 AM   #14
J.W.
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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.
 
  


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