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Re: Ext3 and 3ware RAID5

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.

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

Note blockdev is really something you have to just mess/experiment with.
I went from 12000-26000 and some of the differences between between 1000, or even 500 at times was amazing. My volume is used for storage-only, write speed not too important, so really only did this out of curiosity.

There is also a fair bit of interesting information in 3ware's knowledge base.



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