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Re: tuning, many small files, small blocksize

To: "Hannes Dorbath" <light@xxxxxxxxxxxxxxxxxxxx>
Subject: Re: tuning, many small files, small blocksize
From: "Jeff Breidenbach" <jeff@xxxxxxx>
Date: Sat, 16 Feb 2008 02:24:14 -0800
Cc: xfs@xxxxxxxxxxx
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> That's maybe a bit paranoid, but on the other hand it should give good
> parallelism.

Yes, the goal is fast read performance for small files.

> mkfs.xfs -n size=16k -i attr=2 -l lazy-count=1,version=2,size=32m -b
> size=512 /dev/sda
>
> mount -onoatime,logbufs=8,logbsize=256k /dev/sda /mnt/xfs

This is highly appreciated, thank you very much.

> Requires kernel 2.6.23 and xfsprogs 2.9.5. As said, you might want to
> use an external log device.

I'm running vendor a supplied kernel of 2.6.22 and a quick test shows
the unsupported feature is lazy-count. How big a deal is it? Upgrading
the kernel before April is painful but I'll do it if important. Presumably
there's no simple way to migrate a non-lazy xfs filesytem to a lazy one.

PS. I don't know if this affects any parameters, but the biggest directory
will have approximately 1.5 million files. There are a few in the one to two
hundred thousand range, and then very many in the tens of thousands.


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