Performance problem (high Load average) in Mail Server

[System Administrator]

One way to check is run the command  'top'. Then you will see all the 
programs running the amount of memory and cpu they are using. Type 'shift+m' 
to sort by memory usage on the top screen.
However this is for Fedora. It may work for RHEL or it may not, there may be 
something similar on RHEL.

Regards

Sultanuzzaman Khan
BSS, Dhaka.

----- Original Message ----- 
From: "Mahesh Shinde" <maheshs at cdac.in>
To: "John Rumpelein" <jrumpelein at gmail.com>; 
<redhat-sysadmin-list at redhat.com>
Sent: Thursday, September 22, 2005 7:03 PM
Subject: Re: Performance problem (high Load average) in Mail Server


>
> Dear John,
>
> Yes RHEL3 is uw-imapd based and users also uses WebMail heavily and httpd 
> process takes 25% of CPU resouces.
>
> Can you tell me how to check which user or program/application is eating 
> all the RAM.
>
> The output of "free" command is as follows:
> --------------------------------------------------------------------------
> # free
>              total       used       free     shared    buffers     cached
> Mem:       2565840    2547952      17888          0      37200    2269280
> -/+ buffers/cache:     241472    2324368
> Swap:      2048248     423556    1624692
> -------------------------------------------------------------------------
>
> Regards,
> Mahesh
>
> On Thu, 22 Sep 2005, John Rumpelein wrote:
>
>> What's eating all the RAM?
>>
>> There's a whitepaper on converting to dovecot from uw-imapd (is RHEL3
>> uw-imapd based?) which describes performance issues like this.
>>
>>
>> On 9/22/05, Mahesh Shinde <maheshs at cdac.in> wrote:
>>>
>>> We have a Mail Server with following Hardware/Software configuration.
>>>
>>> IBM X-345 Intel-based Server
>>> DUAL Intel Xeon 2.6 GHz
>>> 2.5 GB RAM
>>> 3 Nos. 72 GB HDD
>>>
>>> OS: Red Hat Enterprise Linux 3 AS Update 5
>>> kernel: 2.4.21-32.0.1.ELsmp
>>>
>>> We are regularly updating the recommended patches from Red Hat Network 
>>> on
>>> Mail Server and it was working fine. But from last 15 days we are facing
>>> severe load problems due to which server gets busy and user experencing
>>> low response/time-outs while accessing mails from their email clients.
>>>
>>> We observed that the busiest process is usually kscand, and overall 
>>> kscand
>>> and kswapd have the highest CPU utilization times.
>>>
>>> As per recent test the server perform well after initial boot, but after
>>> some time only 20 MB of free memory space left out of total 2.5 GB RAM 
>>> and
>>> around 1 GB swap space get used out of 2 GB of swap memory. After that
>>> kscand gets much busier and CPU load seems to increased wildly.
>>>
>>> Please provide us solution to this critical problem at the earliest.
>>>
>>> Regards,
>>> Mahesh Shinde
>>> C-DAC, Pune
>>>
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>>>
>>
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