Re: Incremental backup for a raid1

[Austin S Hemmelgarn <ahferroin7@gmail.com>]

On 2014-03-14 09:46, George Mitchell wrote:
> Actually, an interesting concept would be to have the initial two drive
> RAID 1 mirrored by 2 additional drives in 4-way configuration on a
> second machine at a remote location on a private high speed network with
> both machines up 24/7.  In that case, if such a configuration would
> work, either machine could be obliterated and the data would survive
> fully intact in full duplex mode.  It would just need to be remounted
> from the backup system and away it goes.  Just thinking of interesting
> possibilities with n-way mirroring.  Oh how I would love to have n-way
> mirroring to play with!
That can already be done, albeit slightly differently by stacking btrfs
RAID 1 on top of a pair of DRBD devices.  Of course, this doesn't
provide quite the same degree of safety as your suggestion, but it does
work (and DRBD makes the remote copy write-mostly for the local system
automatically).