Subject: Re: horrible raidframe performance on 2.0-RC5
To: Egervary Gergely <email@example.com>
From: Greg Oster <firstname.lastname@example.org>
Date: 12/06/2004 12:06:46
Egervary Gergely writes:
> > Another data point - I'm running 2.0_RC4 from October 8, and it's
> > working just dandy here (XP2000+, 512MB ram, 4 RF mirrors on a pair
> > of 120G PATA disks).
> Thank you for all your replies. The problem is somewhat strange,
> and I cannot use the proliant box for testing now - it's running
> as a production server w/1.6.2 for 3 days flawlessly.
> (okay, it's just a workaround for now)
> I _really_ want to reproduce this problem on my desktop box, but
> it works good with 2.5-RC5. Hmmm...
> Anyway, if you are running raidframe with RAID level 5, could you please
> test the performance?
> RAID component tests: (Seagate 120GB ATA 7200RPM on ICH5)
> dd if=/dev/rsd0d of=/dev/null bs=512 count=512k shows ~4 MBytes/sec
dd if=/dev/rwd1d of=/dev/null bs=512 count=512k
268435456 bytes transferred in 51.511 secs (5211225 bytes/sec)
dd if=/dev/rwd2d of=/dev/null bs=512 count=512k
268435456 bytes transferred in 43.815 secs (6126565 bytes/sec)
> dd if=/dev/rsd0d of=/dev/null bs=32k count=8k shows ~59 MBytes/sec (very
dd if=/dev/rwd1d of=/dev/null bs=32k count=8k
268435456 bytes transferred in 4.833 secs (55542200 bytes/sec)
dd if=/dev/rwd2d of=/dev/null bs=32k count=8k
268435456 bytes transferred in 7.349 secs (36526800 bytes/sec)
> RAID overall tests: (raid 5 with 3 similar disks as above)
> dd if=/dev/rraid0d of=/dev/null bs=512 count=512k shows ~2.3 MBytes/sec
dd if=/dev/rraid3d of=/dev/null bs=512 count=512k
268435456 bytes transferred in 60.073 secs (4468487 bytes/sec)
> dd if=/dev/rraid0d of=/dev/null bs=32k count=8k shows ~25 MBytes/sec
dd if=/dev/rraid3d of=/dev/null bs=32k count=8k
268435456 bytes transferred in 7.658 secs (35052945 bytes/sec)
> It should be faster, isn't it?
It would seem to be a little on the slow side... In my case, the
disks are different (1/2 of an 80GB and 2 40GBs) so it's a bit hard
to compare against.
> sectPerSU is set to 128
> (makes no sensible difference with lower or higher value)
What does your disklabel look like? Does raid0a start at '0' or some
offset? A sectPerSU value of 32 or 64 should make a *huge*
difference (vs. 128) for a 3-disk RAID 5 set, especially for
writes through the filesystem.