Ext3 and 3ware RAID5

[Sean O Sullivan]

Alex Bligh wrote:
> 
> 
> --On 15 April 2006 07:33 -0400 Joshua Baker-LePain <jlb17 at 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.

Regards,

Sean