Date: Thu, 5 Feb 1998 00:40:12 +0100 (MEZ) From: Robert Eckardt <roberte@MEP.Ruhr-Uni-Bochum.de> To: dwhite@resnet.uoregon.edu Cc: perl@netmug.org, freebsd-questions@FreeBSD.ORG Subject: Re: ccd mirroring Message-ID: <199802042340.AAA00646@ghost.mep.ruhr-uni-bochum.de> In-Reply-To: <Pine.BSF.3.96.980204123341.15689H-100000@gdi.uoregon.edu> from Doug White at "Feb 4, 98 12:36:02 pm"
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It was Doug White who wrote: > On Tue, 3 Feb 1998, Michael Haro wrote: > > > I was reading about ccd and how it can be used to mirror data kinda like > > RAID level 1. > > > > If one of the drives crash, how would I remedy the crash? > > The drives I currently have are different sizes, would this cause a > > problem when using ccd? > > Yes, it's not permitted. CCD must use homogenous disks. > > Recovering a mirrored disk involves bringing over a disklabel and fixing > some other bits. It's not a seamless recovery, but the data is still > there. I'm not familiar with the entire procedure but someone probably > figured it out at some point and posted about it :) A while ago, I had this problem. One of my mirrored disks produced more and more read errors until it effectively stopped working. All I had to do was to reconfig ccd to use only one disk as a "mirrored" ccd disk. After replacing the defective one with a new (much larger :-) one, I simply made a partition of the size (same number of blocks in disklabel) as the old one and copied with `dd' the first ccd disk (actually only the ccd-partition, of course) to the new partition. (Copying etc. was done with the ccd filesystem unmounted and not ccdconfig'd, of course.) Then, all I had to do was to ccdconfig and mount again. (not to forget to tell ccd in ccd.conf to use both disks again. :-) BTW, a question: I understand that for mirroring ccd writes data on both disks "simultaneously". But what about reading ? Will it catch inconsistencies between the two disks ? Hope it helps, Robert -- Robert Eckardt \\ FreeBSD -- solutions for a large universe.(tm) RobertE@MEP.Ruhr-Uni-Bochum.de \\ What do you want to boot tomorrow ?(tm) http://WWW.MEP.Ruhr-Uni-Bochum.de/~roberte For PGP-key finger roberte@gluon.MEP.Ruhr-Uni-Bochum.de
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