From: Bernd Schubert <bernd-schubert@gmx.de>
Subject: Re: nfs performance problem
Date: Thu, 25 Oct 2007 15:53:51 +0200
Message-ID: <200710251553.52138.bernd-schubert@gmx.de>
References: <20071025131029.GH8334@barnabas.schuldei.org>
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Cc: Andreas Schuldei <andreas@schuldei.org>
To: nfs@lists.sourceforge.net
In-Reply-To: <20071025131029.GH8334@barnabas.schuldei.org>
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Hello Andreas,

On Thursday 25 October 2007 15:10:29 Andreas Schuldei wrote:
> lotta:/var/disks/sda on /var/disks/sda type nfs
> (ro,hard,intr,proto=tcp,rsize=32k,addr=217.213.5.44) lotta:/var/disks/sdb

try to increase rsize and wsize as much as possible, the maximum can be 
adjusted in /proc/fs/nfsd/max_block_size on the nfs server.

>
> but when i then do the same dd again on the client i get
> disappointing 60-70Mbyte/s altogether. from a single disk i get
> ~25Mbytes/s on the client side.
>
> i played with some buffers /proc/sys/net/core/rmem_max and
> /proc/sys/net/core/rmem_default and increased them to 256M on the
> client.
>
> i was suspecting that the nfs server reads the files in too small
> chunks and tried to help it with
>
> for i in a  h i  ; do ( echo $((1024*6)) >
> /sys/block/sd$i/queue/read_ahead_kb ) ; done

Are your partitions on lvm or md? This wouldn't help then, AFAIK for lvm you 
can't do it via /sys, but must always use blockdev

>
> to get it to read in the files in one go.
>
> I would hope to at least double the speed. do
> you have a benchmark tool that can tell me the latency? i tried
> iozone and tried forcing it to only do read tests and did not get
> any helpfull error or output at all.

First of all, what is you *local* performance?


Cheers,
Bernd

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