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Re: Ext3 and 3ware RAID5

On Sat, 15 Apr 2006 at 12:57pm, Sean O Sullivan wrote

Alex Bligh wrote:

--On 15 April 2006 07:33 -0400 Joshua Baker-LePain <jlb17 duke edu> wrote:

No idea, but I suffer the same problem with a 9550SX-4 with SATA3
drives. I don't think ext3 is the problem as dd gives much the same
behaviour (you might want to try it). My reluctant conclusion is
that the 9550SX is just dog slow, which is why the drives are currently
sitting idle. I would love someone from 3ware to disprove this.

When ext2 is almost 2X faster than ext3 at writing, it points pretty
firmly at something in the journaling code (IMO).  And a journaling FS
can do decently with this hardware, as XFS also gets ~300MB/s writing.

I had similar problems with 9500S-8, and searched about, and eventually found some useful information.
Try mounting the volume with the 'noreservation' option.

AFAIK, that bug was fixed in the most recent centos/RHEL kernel. In any case, noreservation made no difference.

Also, it is well worth your time setting 'blockdev'
for example : blockdev --setra 20000 /dev/sde
and this put this in /etc/rc.local

Yeah, I've already played around with blockdev a lot. It made some difference, but nothing extraordinary.

Joshua Baker-LePain
Department of Biomedical Engineering
Duke University

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