[linux-lvm] Fun and games with mirroring
Stuart D Gathman
stuart at bmsi.com
Tue May 22 17:57:10 UTC 2012
Long ago, Nostradamus foresaw that on 05/22/2012 10:50 AM, Vic would write:
> p.s. The reason I want to do this with LVM mirrors rather than MD RAID is
> that this is potentially a very useful way of grabbing a backup snapshot
> of a machine prior to some risky operation - it allows me to "fork" a
> machine onto two sets of media. But if it leaves the result unbootable,
> that's something of a problem...
>
LVM RAID is mainly used for pvmove at the moment. LVM has a ways to go
to match ZFS or AIX in LVM mirroring features. MD RAID takes a
snapshot just fine. Add the mirror with mdadm, sync it, and "fail" the
mirror and remove it before physically removing the drive. I can see
the issue with multiple PVs, however. There is no atomic way to fail
multiple mirrors at once.
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