[CentOS] Server hangs on CentOS 5.5

Tue Mar 8 18:20:02 UTC 2011
Michael Eager <eager at eagerm.com>

Brian Mathis wrote:
> On Tue, Mar 8, 2011 at 12:24 PM, Michael Eager <eager at eagerm.com> wrote:
>> Hi --
>>
>> I'm running a server which is usually stable, but every
>> once in a while it hangs.  The server is used as a file
>> store using NFS and to run VMware machines.
>>
>> I don't see anything in /var/log/messages or elsewhere
>> to indicate any problem or offer any clue why the system
>> was hung.
>>
>> Any suggestions where I might look for a clue?
> 
> Please be more specific when you say it "hangs".  Does it just pause
> for a minute and then continue working, or does it freeze completely
> until you reboot it?  Does it respond to s "soft" reboot like
> Ctrl-Alt-Del, or do you need to hard power it off?

System is unresponsive.  Monitor blank, no response to keyboard,
no response to remote ssh.  Hit reset to reboot.

The only indication that I had that there was a problem (other
that attached systems were not accessing files) was that the fan(s)
on the server were louder than normal.

> Since this is an NFS server I'm going to guess there might be a lot of
> IO.  Maybe there is some large IO load going on, like maybe all your
> VMs are running anti-virus scan at the same time, or something like
> that.

At the time, should be very low NFS load.

> To troubleshoot, I recommend installing the 'sar' utilities (yum
> install sysstat) and then reviewing the collected data using the
> 'ksar' utility (http://sourceforge.net/projects/ksar/).  sar/ksar are
> good for tracking down acute problems.

Thanks for the suggestion.  I'll look into sar.


-- 
Michael Eager	 eager at eagercon.com
1960 Park Blvd., Palo Alto, CA 94306  650-325-8077