Date: Wed, 28 Mar 2001 01:40:27 +0100 From: Brian Somers <brian@Awfulhak.org> To: Greg Lehey <grog@lemis.com> Cc: Brian Somers <brian@Awfulhak.org>, "Michael C . Wu" <keichii@peorth.iteration.net>, dillon@FreeBSD.ORG, fs@FreeBSD.ORG, hackers@FreeBSD.ORG, brian@Awfulhak.org Subject: Re: Vinum stripe size (was: tuning a VERY heavily (30.0) loaded server) Message-ID: <200103280040.f2S0eSc03825@hak.lan.Awfulhak.org> In-Reply-To: Message from Greg Lehey <grog@lemis.com> of "Wed, 28 Mar 2001 09:50:34 %2B0930." <20010328095034.M1161@wantadilla.lemis.com>
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> On Tuesday, 27 March 2001 at 9:39:36 +0100, Brian Somers wrote:
> >> On Tuesday, 20 March 2001 at 11:11:44 -0600, Michael C . Wu wrote:
> >>> [Lengthy email, bear with me please, it is quite interesting.
> >>> This box averages 30.0 load with no problems.]
> >>>
> >>> <snip>
> >>>
> >>> Average file size is about 4K. /home/bbsusers* is on a vinum
> >>> stripe'd volume with 3 Ultra160 9G 10000RPM drives on sym0 at stripe
> >>> size 256K, Greg: I know this should be a prime number,
> >>
> >> No, there's no requirement for it to be a prime number. The only
> >> problem is that with 32 MB cylinder groups and a power of two stripe
> >> size and subdisk count, you end up with all the superblocks on one
> >> subdisk, which is a performance issue. Choose the stripe size so that
> >> the superblocks are roughly evenly distributed.
> >
> > A performance issue ? Surely you've misspelt ``reliability'' ?
>
> I don't see a reliability issue here.
I believe the only issue with having all your superblocks on one disk
is a reliability thing - if you lose the disk you lose your
superblock(s). Surely the only performance problem would be that of
locality - if you use the partition a bit, that ``problem'' should go
away though.
> Greg
> --
> Finger grog@lemis.com for PGP public key
> See complete headers for address and phone numbers
--
Brian <brian@Awfulhak.org> <brian@[uk.]FreeBSD.org>
<http://www.Awfulhak.org>; <brian@[uk.]OpenBSD.org>
Don't _EVER_ lose your sense of humour !
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