On Wed, Jul 26, 2000 at 08:12:47PM -0700, Gregory Leblanc wrote:
> > Given the code at the moment, I am highly confident that linear, raid0
> > and raid1 should be just as fast in 2.4 as in 2.2.
> > There are some issues with raid5 that I am looking into. I don't
> > know that they affect speed much, though they might.
I doubt it, see below
> Could you be a little more specific? Speed comparisons on disk access?
> Then you can't compare RAID with no RAID effectively. You could compare the
> speed of 2.2/2.4 RAID, and 2.2/2.4 no RAID, but comparisons across would
> seem to be meaningless. Later,
Ok, so here is what I did.
Machine (you might have seen this before, sorry for repetitions)
AMD Athlon 650, 256MB RAM, Abit KA7 Mainboard, VIA Chipset, system on
Fujitsu 20GB IDE disk, 3 Promise PDC20262 UMDA Controller, 6 IBM
DTLA-307045 46GB disks for data.
It runs kernel 2.4.0-test1 (first 3 tests) and 2.4.0-test5-pre3 (rest)
with Andre Hedricks IDE patch and the latest reiserfs.
These are bonnie results:
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
fujitsu 500 2243 39.7 3400 9.4 1422 54.9 1945 75.4 2795 66.3 182.7 29.7
single 500 5025 95.7 20218 81.1 11182 40.5 5214 90.9 26707 48.9 213.2 18.7
raid0, 3 500 4804 83.3 17275 42.7 11067 50.7 5393 92.6 37242 65.2 361.4 28.1
raid0, 4 500 4941 81.8 20920 48.7 13068 66.4 5283 91.0 35318 55.3 394.8 27.6
raid5, 6 500 3009 52.0 3004 4.6 2589 3.6 4411 70.4 18982 13.9 360.5 22.7
where
- "fujitsu" is the system disk
- "single" is a filesystem on a single IBM disk
- "raid0, 3" is a RAID0 array of 3 IBM disks
- "raid0, 4" is a RAID0 array of 4 IBM disks
- "raid5, 6" is a RAID5 array of 6 IBM disks
In between the disks have been freshly partitioned (1 big primary only)
mkraid'ed and given a fresh reiserfs.
It could of course be a combination of reiserfs, Andre Hedrick's IDE patches
and raid. I expected the raid 0 with n disks to get a bit less than
n times the block read performance of 1 disk, and raid5 to have block write
performance of a bit less than single disk, block read performance much
better than for a single disk. Are these expectations unrealistic?
Nils
--
Plug-and-Play is really nice, unfortunately it only works 50% of the time.
To be specific the "Plug" almost always works. --unknown source
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