Date: Wed, 3 Feb 1999 18:12:03 +1030 From: Greg Lehey <grog@lemis.com> To: John Saunders <john.saunders@nlc.net.au> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: advice on setting up a Vinum volume Message-ID: <19990203181203.A1179@freebie.lemis.com> In-Reply-To: <Pine.LNX.3.95.990203181240.27450B-100000@nhj.nlc.net.au>; from John Saunders on Wed, Feb 03, 1999 at 06:22:58PM %2B1100 References: <19990203171610.Z1179@freebie.lemis.com> <Pine.LNX.3.95.990203181240.27450B-100000@nhj.nlc.net.au>
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On Wednesday, 3 February 1999 at 18:22:58 +1100, John Saunders wrote: > On Wed, 3 Feb 1999, Greg Lehey wrote: > >>> Sustained performance is much better. On my pair of Quantum 6.4GB drives >>> they get approx 7MB/s sustained (dd if=/dev/zero of=file bs=262144 >>> count=1024). With a vinum strip of 256K in size I get sustained >>> 12.5MB/s. Running squid on this setup I can watch the load being >>> distributed by running (systat -iostat 1) >> >> Interesting. Which version of FreeBSD is this? Are you using the >> standard vinum, which includes slow debugging aids, or have you >> compiled them out? > > This is done with RELENG_3 cvsupped about a week ago. I did a recent cvsup > and noticed a lot of vinum changes, so it was prior to the lastest > round of changes. Particularly the vinum_slices -> vinum_disks change > bit me (I use rc.conf.local for host config). > > The machine is a PII-350MHz/100MHz bus with 128MB SDRAM so I think any CPU > intensive debug would be dealt with rather quickly. There's a certain truth to that. Some of the debug stuff (like the memory allocation) is painfully slow, but it's probably still faster than a disk. You might like to try to change the parameters in the Makefiles (/usr/src/sbin/vinum/Makefile and /usr/src/sys/modules/vinum/Makefile). Remove the parameter -DVINUMDEBUG from both of them, do make all install, and see how things look then. >>> although vinum stats show that one drive seems to be used about 20% >>> more than the other. >> >> I've noticed this too. There's no way this can be a vinum problem (in >> other words, you should see exactly the same distribution when using >> ccd). I suspect that it's an incompatibility between ufs and the >> stripe size. I suspect that you may end up with all super blocks on >> one drive. It would be interesting to calculate what stripe size >> would balance the cylinder groups across the drives. > > Is there anything wrong with a strip size that is not a power of 2? Not that I know of :-) It would be a bug if it were. > Although it still would have to be a multiple of the block size. Right, everything's a multiple of the block size. It also needs to be a fraction of the volume size. > On Linux the mke2fs command has an option to specify the stripe size > and it does some tweaks to avoid putting super blocks on the same > drive. This is new to me. I didn't know that ext2fs knew anything about striping. > With the ufs 32MB cylinder groups I woudln't be surprised if if all > super blocks were on the same disk. Anyone for prime number stripe > sizes? Try it and tell me :-) Greg -- When replying to this message, please copy the original recipients. For more information, see http://www.lemis.com/questions.html See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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