SUMMARY: Re: detaching a mirror from a trans device -- safe?

From: Adam and Christine Levin (
Date: Fri Oct 27 2000 - 14:22:36 CDT

Thanks to Michael Sullivan <> and Darren Dunham
<>. Both agreed that unmounting the file system first is
the best way to go. Since that's possible, that's what I plan to do. It
would probably be OK to sync and then detach, but I want to be 100% safe,
and these file systems are solely for use by the app, so once the app is
shut down, those file systems will be quiescent. The unmount adds some
piece-of-mind, and will potentially avoid some fsck complaints later.


On Fri, 27 Oct 2000, Adam and Christine Levin wrote:
> Ok, I've got what I hope is an interesting question.
> We're using a multiple-mirror scheme to backup some sensitive data. The
> way we're doing it is like so:
> disk1 <-> disk2 are mirrored
> disk3 is attached to that mirror.
> disk4 is an additional disk.
> Every week, we detach disk3 and attach disk4. At any given time, we have
> a two-way mirror (disks 1&2), a third mirror piece that's only missing
> during the resync, and a fourth disk that's got a snapshot of the files.
> The question is this: we're using a trans device to take advantage of UFS
> logging (this is all DiskSuite 4.1 under Solaris 2.6, fully
> patched). We've got several small slices on various disks that are
> mirrored together to be the logging piece.
> Once I know the filesystem is quiescent (application has been fully shut
> down), can I just detach the third mirror piece? Should I unmount the
> filesystem, detach the mirror, and then remount the filesystem, just to be
> extra sure?
> Thanks,
> -Adam

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