[conspire] md raid as backup?
togo at of.net
Tue Dec 19 21:28:22 PST 2006
I've been playing with USB2 drives and md RAID, both in raid1 (n-way
mirroring) and the new raid10 (raid1+raid0 but better: n-way
redundancy spread among m drives). (Sadly raid10 isn't really
growable, but growable raid5 is available in the bleeding edge
One strange idea has popped into mind- maybe you folks can tell me if
my thinking is
(a) out of the box
(b) out of the mind
I spend my days in three usual places the office, the home with the
wife and cats, and the home near the office. Say I have a USB2 (for
low price and hotpluggability) at each place. And I'm concerned about
laptop hard-drive failure, since I've had two fail in the past year.
Say I set up my notebook to have /home mounted in a RAID1 partition.
When I use my laptop alone it's running with just md in a
all-failed-but-internal mode, which works, and when I sit down at
location X, I plug in an external USB2 drive and mdadm --re-add it,
and it proceeds to use spare I/O cycles to sync any changes I've made
since it saw the laptop last. When I go, I hibernate the laptop, and
that USB2 drive gets failed until I sit down at location X again.
Essentially I'd run a 4-way mirrornig RAID of which at any given time
two or three would be "failed" and one or two would be active. And if
my notebook drive ever fails, I have three copies at reasonably recent
states that should automatically negotiate the latest good /home.
Is there anything wrong with this other than it being unconventional?
Tony Godshall (g)
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