Re: ext3 sucks

[Arjan van de Ven <arjan infradead org>]

On Tue, 2005-10-25 at 22:38 -0500, Aleksandar Milivojevic wrote:
> Joshua Baker-LePain wrote:
> > On Tue, 25 Oct 2005 at 10:12am, Kostas Georgiou wrote
> > 
> >> With 3ware cards i get slightly better results (for our workload) in 
> >> RHEL4
> >> with the following settings:
> >> vm.dirty_expire_centisecs = 1000
> >> vm.dirty_writeback_centisecs = 500
> >> vm.dirty_ratio = 5
> >> vm.dirty_background_ratio = 10
> > 
> > These numbers had no effect for me, but I'm likely to play with 'em a 
> > bit more.
> 
> I've got an 3ware 7500-8 card yesterday that I had to configure for 
> RAID-5, and experienced exactly the same lack of performance Joshua is 
> having problems with.  I know that 7500-8 isn't RAID-5 speed champion 
> (not even close), but I believe the card itself should be faster than 
> what I got (around 18 MB/sec for ext3 and 35 MB/sec for ext2).
> 
> The above settings also make almost no difference to me.  What made 
> difference was switching from ext3 to ext2, almost double write speed, 
> instantly.  The read speed stayed the same.  Interestingly, the rewrite 
> Bonnie test gave almost identical speed with both ext2 and ext3.


for me always this got resolved by changing the ext3 journal mode.. I
then get back the ext2 write performance....