Performance problem (high Load average) in Mail Server

[Mahesh Shinde]

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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