Re: ext3 sucks

[Joshua Baker-LePain <jlb17 duke edu>]

On Mon, 24 Oct 2005 at 8:05pm, Arjan van de Ven wrote

> On Mon, 2005-10-24 at 13:49 -0400, Joshua Baker-LePain wrote:
> > Well, on my servers with 3ware 7500-8 boards in hardware RAID5 mode it
> > does, and I thought the subject line might get a bit of attention.
> > Basically, no matter how I tune, I can't get anything even resembling
> > decent write speed out of hardware that used to run quite well.  I've
> > played with tuning both 'blockdev --setra' as well as
> > /sys/block/$DEVICE/queue/nr_requests, and nothing increases ext3 write
> > speed over 20MB/s on a single board.  To prove it isn't hardware, I also
> > tested using the centosplus kernel and XFS on the exact same array.  XFS
> > was able to get over 40MB/s on a single board.  When doing a RAID0 over 2
> > boards, ext3 maxed out at 35MB/s while XFS was able to do >100MB/s.  All
> > these tests were done using bonnie++ and a filesize >4x the amount of
> > system RAM.
>
> did you set the journalling mode to write-back?
> The default ext3 journalling mode is more strict than the XFS one, but
> slower (so the trade off is data integrity vs speed); XFS is more
> comparable with the writeback type. The performance difference is mostly
> visible on new file creation...
First off, I'd like to apologize for the subject line.  It's been a bad 
few days, but that's no excuse to start a thread out like that.  *sigh*

Thanks for the suggestions.  I tested with 3 different sets of my "tweak 
settings", and setting 'data=writeback' actually slowed things down (if it 
had any effect).

Also, to answer the question about versions, all ext3 testing was done 
with 2.6.9-11.ELsmp, and all XFS testing was done with 
2.6.9-11.106.unsupportedsmp (centosplus) -- the box is essentialy at U1. 
And I'm using bonnie++-1.03a.

If there are any more suggestions/tweaks/patches, I'd love to hear 'em. 
Thanks again.

--
Joshua Baker-LePain
Department of Biomedical Engineering
Duke University