Date: Tue, 27 Mar 2001 18:11:41 +0930 From: Greg Lehey <grog@lemis.com> To: Alfred Perlstein <bright@wintelcom.net> Cc: "Michael C . Wu" <keichii@peorth.iteration.net>, dillon@FreeBSD.ORG, fs@FreeBSD.ORG, hackers@FreeBSD.ORG Subject: Re: Vinum stripe size (was: tuning a VERY heavily (30.0) loaded server) Message-ID: <20010327181141.H1161@wantadilla.lemis.com> In-Reply-To: <20010327000503.T9431@fw.wintelcom.net>; from bright@wintelcom.net on Tue, Mar 27, 2001 at 12:05:03AM -0800 References: <20010320111144.A51924@peorth.iteration.net> <20010327171653.G1161@wantadilla.lemis.com> <20010327000503.T9431@fw.wintelcom.net>
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On Tuesday, 27 March 2001 at 0:05:03 -0800, Alfred Perlstein wrote: > * Greg Lehey <grog@lemis.com> [010326 23:47] 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. >> >>> can we safely use <150K stripe sizes? >> >> Safely, yes. But as somebody else has observed, you are probably disk >> I/O bound. Reducing the stripe size will tend to increase the disk >> load, though probably not very much if your files are all 4 kB. I'd >> go for something like 273 kB stripes. > > Do you think it'd be worth it to have vinum carp about what may > be a non optimal stripe size? > > "Warning N is probably a bad idea for a stripe size, see docs" Only if it can recognize the fact correctly. Greg -- Finger grog@lemis.com for PGP public key See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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