Date: Wed, 3 Mar 2004 16:57:43 -0500 From: Charles Swiger <cswiger@mac.com> To: Stefan Cars <stefan@snowfall.se> Cc: Free BSD Questions list <freebsd-questions@freebsd.org> Subject: Re: 1 processor vs. 2 Message-ID: <CC810421-6D5D-11D8-85AD-003065ABFD92@mac.com> In-Reply-To: <20040303222612.W39053@guldivar.globalwire.se> References: <BC6A0533.1DC4C%joe@jwebmedia.com> <40452715.5030304@mindcore.net> <200403031453.49069.danny@ricin.com> <20040303160658.GA32905@happy-idiot-talk.infracaninophile.co.uk> <20040303222612.W39053@guldivar.globalwire.se>
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On Mar 3, 2004, at 4:26 PM, Stefan Cars wrote: > Okey, but if you would compare RAID-1 on two disks compared to RAID-5 > on > three disks then ? What would be the faster ? RAID-1 will be about 50% faster than RAID-5 doing reads regardless of size, and will also be *much* faster doing small writes-- by a factor of 4, perhaps. [ There is a potential optimization for RAID-5 using very large writes-- ie, bigger than the RAID interleave size * (# of disks - 1)-- that might make it more comparable with RAID-1's performance, only I believe FreeBSD breaks up large I/O requests into 32K or so, thus there generally never is the potential to not read the data before writing. ] -- -Chuck
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