System hang due to high iowait

[Carlos Antonio Gomez]

I do not speak English :-) 

RedHAt AS3 Update 1 


The problem is that the server hangs.  The daemons start to die and the
server only functions at the kernel level.  You can remove the network
cable and it notifies you on the console.  You insert the network cable
and it also notifies you.  If you browse to Webmin, it responds with the
authorization page, but authentication fails because the daemon died. 
You can telnet to the server on different ports and it connects, but it
waits for the login banner, etc.

I made a script which logs the load on the server each minute and when I
look at this I realize mailman is the problem.  The load average goes up
to 60% (?) when normally it's only 4%.  I browsed the mailman logs and
for the last few hangs, log entries coincide with mail sent to lists,
but it happens with small or large lists.



The hanging of the server is happening whether mail is sent to the small
or large lists.  I've tried troubleshooting the hardware and through
testing I'm able to send mail to the lists and the server hangs, but not
every time.  This makes me thinkg it's not postfix or mailman, but
possibly some other daemon.




----- Original Message ----- 
From: <csu4 at fedex.com>
To: <redhat-list at redhat.com>
Sent: Monday, October 04, 2004 1:46 AM
Subject: System hang due to high iowait


> Hi there,
> 
> Could anyone help to find the system hung problem? The box
> is running RHEL 3AS Update3. Whenever I do a massive data
> transfer (such as rcp from another box to this box), after
> certain time (around six to seven hours), this box would
> hang up. I could see the top output even it's hung, and it
> showed that the iowait is 99% and system contributed another
> 1% making the server moving nowhere.
> 
> The box connected to a HP MSA500 Smart Array Storage, thru
> multipath (I enabled it following the user guide) connection.
> The filesystem is ext3 format. Any problem here?
> 
> 
> 
> 
> 
> Thx & Rgds,
> 
> 
> SCHYU
> 
> 
> 
> 
> 
> 
> 
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