Date: Tue, 16 Apr 2002 09:19:01 -0700 (PDT) From: Scott Hess <scott@avantgo.com> To: Chris Dillon <cdillon@wolves.k12.mo.us> Cc: David Drum <david@mu.org>, FreeBSD DB List <freebsd-database@FreeBSD.ORG> Subject: Re: Raid configuration Message-ID: <Pine.LNX.4.44.0204160908060.5530-100000@river.avantgo.com> In-Reply-To: <20020414212607.X83685-100000@mail.wolves.k12.mo.us>
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Additionally, consider two setups: RAID10 (stripe of mirror) +---------+ |+-------+| || A = B || |+-------+| |+-------+| || C = D || |+-------+| +---------+ RAID01 (mirror of stripes) +-----------+ |+---+ +---+| || A | | B || || |=| || || C | | D || |+---+ +---+| +-----------+ Both have the same uptime for single-disk failures. For two-disk failures, RAID10 stays up for 2/3 of the cases, while RAID01 only stays up in 1/3 of the cases. Later, scott On Sun, 14 Apr 2002, Chris Dillon wrote: > On Sun, 14 Apr 2002, David Drum wrote: > > > > And when you only have a four-drive configuration, it makes no > > > difference which one you use since the chances of a total failure > > > is exactly the same either way. Any more drives than that and you > > > definately want RAID10. :-) > > > > The chances of total failure may be the same, but the effort > > required to rebuild the RAID is not. If you have 4 9GB disks in a > > RAID 0+1 and one goes bad, you have to mirror 18GB once the drive is > > replaced. If you have a RAID 1+0, you only have one drive to > > mirror, and not a stripe. > > Ah, yes, I hadn't thought of what it would take to rebuild one. In > that case, RAID 0+1 looks like the loser in all situations. > > -- > Chris Dillon - cdillon@wolves.k12.mo.us - cdillon@inter-linc.net > FreeBSD: The fastest and most stable server OS on the planet > - Available for IA32 (Intel x86) and Alpha architectures > - IA64, PowerPC, UltraSPARC, and ARM architectures under development > - http://www.freebsd.org > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-database" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-database" in the body of the message
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