Date: Sun, 9 Nov 2003 13:34:50 -0800 From: David Schultz <das@FreeBSD.ORG> To: Christian Laursen <xi@borderworlds.dk> Cc: Lukas Ertl <l.ertl@univie.ac.at> Subject: Re: geom_mirror implementation Message-ID: <20031109213450.GB13982@VARK.homeunix.com> In-Reply-To: <868ympydcx.fsf@borg.borderworlds.dk> References: <20031109003617.K626@korben.in.tern> <20031109023041.GA9171@VARK.homeunix.com> <868ympydcx.fsf@borg.borderworlds.dk>
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On Sun, Nov 09, 2003, Christian Laursen wrote: > David Schultz <das@FreeBSD.ORG> writes: > > > On Sun, Nov 09, 2003, Lukas Ertl wrote: > > > Hi hackers@, > > > > > > I've played around with GEOM a bit and beefed up geom_mirror, which is > > > already in the tree but not built yet. > > > > > > You can find the patch at <http://mailbox.univie.ac.at/~le/geom.diff>. > > > > Hmm...I believe geom_mirror is supposed to be an example, and > > geom_ccd is supposed to be the production mirroring implementation. > > ccd does have its quirks, though... > > Last time I checked ccd needed to be manually reconfigured to run in > degraded mode and sync is not possible. In my book that's not good > enough for production. > > Furthermore it would be nice with a mirror implementation that > automatically syncs the mirror after an unclean shutdown. Yeah, RAID support in FreeBSD is in a rather sorry state right now. ccd(4) doesn't work with ATAng on my machine without causing panics and data corruption, raidframe is broken in -CURRENT, and vinum tends to lag behind changes and break. But that doesn't mean that the right solution is to add a *fourth* incompatible RAID implementation. If there's a good reason ccd(4) is harder to fix than geom_mirror, then you might want to talk to phk about rewriting geom_ccd based on geom_mirror. I believe scottl and phk have plans to fix raidframe, though, which would address a lot of the present limitations.
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