Date: Sat, 29 Nov 1997 17:25:26 +1030 From: Greg Lehey <grog@lemis.com> To: David Dawes <dawes@rf900.physics.usyd.edu.au> Cc: hackers@FreeBSD.ORG Subject: Re: Drive Mirroring Message-ID: <19971129172526.39614@lemis.com> In-Reply-To: <19971129165905.08819@rf900.physics.usyd.edu.au>; from David Dawes on Sat, Nov 29, 1997 at 04:59:05PM %2B1100 References: <Pine.BSF.3.96.971128192019.1020A-100000@trojanhorse.ml.org> <199711290422.PAA23032@mother.sneaker.net.au> <19971129151057.57891@lemis.com> <19971129165905.08819@rf900.physics.usyd.edu.au>
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On Sat, Nov 29, 1997 at 04:59:05PM +1100, David Dawes wrote: > On Sat, Nov 29, 1997 at 03:10:57PM +1030, Greg Lehey wrote: >> On Sat, Nov 29, 1997 at 03:22:12PM +1100, Andrew Kenneth Milton wrote: >>>> Would a software RAID implementation be able to cope with having a drive >>>> removed? >>> >>> The last implementation I saw of software RAID on Solaris didn't >>> (about two years ago). >>> >>> It wouldn't boot from the secondary drives, >> >> Booting is a different matter. It's a lot more complicated, since you >> need to explain RAID to the bootstrap. I don't think that's >> feasible. But once the system is up and running, all other file >> systems should be able to be RAID. > > The Veritas software that Sun supplies with their Sparc storage arrays > these days does allow this. It was one of the first things I tried > (having a mirrored boot disk, removing the one it usually boots from, > and booting from the other). In the configuration I tested, the boot > disk and its mirror were both "normal" disks attached to the primary > scsi controller, and not disks in the storage arrays. Mirroring is the > only RAID type supported for boot disks though. Yes, Tandem supplies Veritas as well, and Version 2 (which is even more convoluted than Version 1) supports booting from a Veritas volume. It does this by imposing significant restrictions on the format of root volumes. It's not nice--I'd guess that it would make more sense to have a really intelligent boot to handle things until Veritas (or whatever) was up and running. For the benefit of those who don't know Veritas: it runs as a number of processes, notably the Volume Daemon. Until that's up and running, you can't mount Veritas volumes (virtual disks). Greg
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