Performance problem (high Load average) in Mail Server

[Alan]

Mahesh Shinde wrote:
> 
> 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.


"ps aux" or "top" will tell you VSZ and RSS.

Cheers,

Alan










> 
> 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
>>>