Date: Wed, 27 Oct 2004 08:05:10 -0400 From: Chuck Swiger <cswiger@mac.com> To: miha@ghuug.org Cc: freebsd-stable@freebsd.org Subject: Re: question on vinum Message-ID: <417F8EF6.9060304@mac.com> In-Reply-To: <200410271114.36794.miha@ghuug.org> References: <200410270027.47092.miha@ghuug.org> <1098855222.15580.81.camel@emperor> <200410271114.36794.miha@ghuug.org>
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Mikhail P. wrote: > On Wednesday 27 October 2004 05:33, secmgr wrote: [ ... ] >> If you want to do that, then you want raid5. If either a concat or >> stripe set looses a drive, the data will need to be restored. > > Are there known methods/techniques to restore data from failed concat or > stripe volumes? Certainly. It's known as "taking a backup", perhaps to a tape drive or some other form of storage. If you don't have a backup, and you lose a disk in a RAID-0 config, you will effectively lose all of the data. [ ... ] > Does striping require an additional drive too? No. > Or it is very similar to > concat, except for it stores data across all the spindles? Yes, that's right. > Does it also mean that it is harder to recover stripped volume? The question isn't well-phrased: you can't recover data from either if you lose a drive. > As for raid5 - it requires an additional drive. Are there any requirements for > the drive? E.g. would it work as having 3 x 200GB for stripe + additional > 20GB drive that will be used for control blocks? No. All of the drives need to be the same size. With RAID-5, which drive is used to hold parity data rotates on a stripe-by-stripe basis to balance out the load. > And what happens here if > 20GB drive fails - will I be able to rebuild it and continue using raid? You can rebuild a RAID-5 volume if a single drive fails without losing data. -- -Chuck
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