[OpenAFS-devel] fileserver parameters

[Roland Kuhn]

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Hi Niklas!

On Jun 20, 2005, at 10:19 AM, Niklas.Edmundsson@hpc2n.umu.se wrote:

> On Sat, 18 Jun 2005, Tom Keiser wrote:
>
>
>>> So, can anybody comment on these numbers? Those are dual Opteron
>>> boxes with enough RAM, so please make some suggestions what  
>>> options I
>>> should try to get more like the real performance of a fileserver...
>>>
>
> What kernel? What underlying filesystem?
>
vanilla 2.4.31, reiserfs.

> The performance figures you mentioned when talking directly to the  
> raid, are they when doing IO on a filesystem that are similar to  
> the AFS IO pattern (ie accessing a large number of small files)?  
> Streaming IO figures are more or less uninteresting when doing AFS  
> in our experience.
>
I haven't had a look yet, but I thought the files were stored also as  
files in /vicep*? Our files are 1.5GB each, so streaming reads should  
be what we need, right?

On the other hand I did the read benchmark (dd) with only one  
process, and the rate went down from 230MB/s to 200MB/s when going  
through the filesystem instead of reading directly from the block  
device.

> If using ext*, go for ext2 and boot the machine with SMP disabled  
> and se what happens. This improved the situation somewhat for us,  
> but this was on a 2.4 kernel tho (albeit 2.6 is said to still have  
> issues wrt ext3 and SMP).
>
Disabling SMP is not an option, I'll have to see where tuning the  
parameters and/or upgrading to 1.3.84 gets me.

> Filesystem-wise, xfs seems to be the best performing (and most  
> robust) filesystem on Linux nowadays, but I don't know whether it's  
> supported to have your /vice* on Linux-XFS...
>
I could try that one, too.

Thanks for your suggestions,
                     Roland

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