Note* rawio will overwrite your data, so be careful!
Here are tests that I ran using a 4 disk array (10k RPM SCSI disks). I have
about 20 datafiles comprising 8 different stripe sizes for 3 different raid
configurations (0,5,1+0) if anyone is interested (Greg?).
Thanks,
brandon
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]On Behalf Of Greg Lehey
> Sent: Friday, September 08, 2000 10:03 PM
> To: Esko Petteri Matinsola; Clark Shishido
> Cc: [EMAIL PROTECTED]
> Subject: Re: Vinum RAID-5 performance problem
>
>
> On Friday, 8 September 2000 at 22:24:51 +0300, Esko Petteri
> Matinsola wrote:
> > Thank you for your last reply about the Promise 100 controller, I got it
> > working with that patch.
> >
> > But now, I have Asus P2L97 mobo with 64MB RAM, 266MHz P2 and 4 Maxtor
> > 54098H8's, two per channel. OS is FreeBSD 4.1-STABLE.
> >
> > When I use vinum with the following config:
> >
> > drive drive0 device /dev/ad0e
> > drive drive1 device /dev/ad1e
> > drive drive2 device /dev/ad2e
> > drive drive3 device /dev/ad3e
> >
> >
> > volume raid0
> > plex org striped 256k
> > sd length 512m drive drive0
> > sd length 512m drive drive1
> >
> >
> > so I have RAID-0 with the master and slave drive from controller one.
> > bonnie -s 512 on that gives me:
> >
> >
> > -------Sequential Output-------- ---Sequential Input-- --Random--
> > -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
> > MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
> > 512 13287 97.3 20237 41.0 8023 25.6 8572 97.8 21442 29.4 128.1 2.2
>
> Please don't use bonnie. It's not measuring what you think it is.
>
> > not bad, even when two drives on the same controller. Next, I
> tried vinum
> > with the following config:
> >
> > drive drive0 device /dev/ad0e
> > drive drive1 device /dev/ad1e
> > drive drive2 device /dev/ad2e
> > drive drive3 device /dev/ad3e
> >
> > volume raid0
> > plex org striped 256k
> > sd length 512m drive drive0
> > sd length 512m drive drive2
> >
> > so I have RAID-0 with the masters from both controllers. bonnie -s 512
> > gives me:
> >
> > -------Sequential Output-------- ---Sequential Input-- --Random--
> > -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
> > MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
> > 512 13263 97.4 21340 43.7 8169 26.1 8572 98.0 25858 36.6 213.4 3.9
> >
> > only a little better, except the seeks.
>
> Of course. The seeks are the only thing which relate to real-life
> performance. Look at the sequential character output, for example.
> It's showing clearly that the bottleneck is the CPU, not the storage
> subsystem. In block writes, the real-world performance of the first
> configuration is in fact worse than what you see there, but since
> bonnie is only writing one file at a time, you don't run into any
> contention problems. You should be using rawio, which will show you
> what the storage system is doing.
>
> > Now next to my problem. When I use vinum with the following config:
> >
> > drive drive0 device /dev/ad0e
> > drive drive1 device /dev/ad1e
> > drive drive2 device /dev/ad2e
> > drive drive3 device /dev/ad3e
> >
> > volume raid5
> > plex org raid5 256k
> > sd length 512m drive drive0
> > sd length 512m drive drive1
> > sd length 512m drive drive2
> > sd length 512m drive drive3
> >
> >
> > so I have RAID-5 with all the drives from both controllers.
> bonnie -s 512
> > gives me:
> >
> >
> > -------Sequential Output-------- ---Sequential Input-- --Random--
> > -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
> > MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
> > 512 2368 17.7 2358 4.8 2016 6.6 8218 94.4 20068 29.1 232.5 4.3
> >
> > read performance and seeks seems OK, but block writes only about 1/9th !
> > As I read from www.vinumvm.org I should get something like 5MBps block
> > writes.
>
> I don't know how you'd find anything at vinumvm.org which tells you
> what to expect from bonnie.
>
> > Have I misunderstood something, configured someting improperly, it's
> > because of only two IDE-controllers or why I get so lousy write
> > performance ?
>
> Well, firstly I don't know what your write performance is. It really
> depends on what you're trying to do. But yes, having only two
> controllers will halve your RAID-5 write performance. Note also that
> with a 256 kB stripe, you'll run into drive contention problems
> because all your superblocks will be on the same subdisk. Take a size
> like 273 kB, for example.
>
> > I could live with 5MBps, if I only could get that ! :)
>
> I'd expect the performance to increase by about 50% or 60% if you use
> four controllers.
>
> On Friday, 8 September 2000 at 12:55:51 -0700, Clark Shishido wrote:
> > At 22:24 +0300 2000.09.08, Esko Petteri Matinsola wrote:
> >>
> >> read performance and seeks seems OK, but block writes only
> about 1/9th !
> >> As I read from www.vinumvm.org I should get something like 5MBps block
> >> writes.
> >>
> >> Have I misunderstood something, configured someting improperly, it's
> >> because of only two IDE-controllers or why I get so lousy write
> >> performance ?
> >
> > Your configuration looks fine.
>
> Well, using master and slave together isn't fine in my book.
>
> > I just recently tried a similar setup using Promise Ultra66 controllers
> > with some Quantum and IBM drives (tried both). I got lousy performance
> > doing sustained writes to a RAID5 volume, using 4 UDMA66 drives each a
> > master on a controller. just doing a cat /dev/zero > blah
> >
> > I just decided to stick with striping and make regular backups.
> > I may try vinum with RAID5 on a SCSI array later.
> >
> > FWIW,
> > FreeBSD 4.1-STABLE
> > Abit BP6 dual 466 Celerons
> > (not using the HPT controller)
> > Promise Ultra66
> > Quantum KA 13.6 gig and IBM Deskstar 30 gig drives
>
> Again, it would be nice to see some real figures. Why aren't you
> using the onboard controller on the BP6?
>
> Greg
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