From: <Jamie.Stevens_at_email.protected>
Date: Tue, 25 Aug 2009 15:48:36 +1000

Hi all,

I've completed some diskspeed tests on cavsi1 using ext3, ext2 and xfs
filesystems. I did all tests using filesizes that would have been
generated by an experiment running at 512 Mbit/s; some with 10s files,
others with 60s files.

I've attached two postscript files to this email. Each shows the results
of the 9 tests I did, and each file corresponds to tests run on one side
of the Xraid (all tests were performed on both Xraid sides to ensure
consistency).

The results show that ext3 is quite a lot slower than ext2 or xfs, even
when tuned for performance. xfs has the highest average speed, with ext2
not far behind. It doesn't appear that changing the filesize has much
effect on the average speed the disks can sustain.

One of the most important things is the minimum speed. The bigbuffer
will start to fill if the speed falls below the required recording rate,
and this will lead to bigbuf skips if the disks don't catch up in time.
ext3 filesystems have a very low minimum speed, as do ext2 filesystems
with 10s files. But with 60s files, both ext2 and xfs do not drop much
below 500 Mbit/s, and xfs can keep its minimum rate up even with 10s files.

cheers
Jamie

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Received on 2009-08-25 15:48:56