High load average mail server 5.3-RELEASE

[Mariano Benedettini]

Thanks for all the replies. It's not a HD problem.
On monday I'll increase the number of nfsd processes and the number of 
nfsiod on the client, setting both to 50,
I think that the nfs performance will be much better :-)

Mariano.

Eric Anderson wrote:
> Francisco Reyes wrote:
> 
>> On Tue, 13 Sep 2005, mariano benedettini wrote:
>>
>>> 91.3% idle
>>
>>
>>
>> CPU is not the problem. :-)
>>
>>
>>> Mem: 1599M Active, 1704M Inact, 311M Wired, 189M Cache, 112M Buf, 14M 
>>> Free
>>> Swap: 2023M Total, 184K Used, 2023M Free
>>
>>
>>
>> Swap is not the problem.
>>
>>
>> Do
>> vmstat 10
>>
>> Watch the output.
>> In particular look at the first 3 columns.
>>  procs
>>  r b w
>>  1 1 0
>>  0 1 0
>>  1 1 0
>>
>> The left most column is CPU, the second column is disk IO.
>>
>> If you have a number in the "b" column and it never hits 0 you have an 
>> I/O problem. You HDs are not catching up.
>>
>> If you are using NFS and the "b" colun is not high and hits 0 some/all 
>> the time then the bottleneck is either the nfs connection or the nfs 
>> server.
>>
>> For example I have some servers that the "b" column would be between 
>> 20 and 60 for a while. I am currently working on removing some of the 
>> load of the machine. In my case more memory would help, but the 
>> computer vendor we bought the machine from has sent us the wrong 
>> memory 3 TIMES!!
> 
> 
> Also, if it is an NFS server, one should check the cpu times on the nfsd 
> processes.  I've found that many times there aren't enough nfsd 
> processes to take the load from many clients.  Increasing the number 
> (double it) often helps this.  The max in 5.3 is 20, but you can easily 
> change it and get around it.
> 
> Eric
> 
> 
> 
>