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Re: [LUG] Software RAID-1 on USB drives

 

On Tue, 20 Oct 2009, ste@xxxxxxxxxxxxxxxxx wrote:

2 USB drives where periodically rsync is run to duplicate drive 1 onto
drive 2.  Drive 1 is static, drive 2 (should) get removed every evening
and taken off-site.

If the two drives were setup in a software-based RAID-1 (mirror)
configuration, would they automatically reconcile any differences when
drive 2 was re-attached?  If not, how can differences between two
software RAID-0 drives be reconciled?  Is there a command that initiate
the reconciliation?  Can this be added to a udev rule so that when
drive 2 is re-attached the reconciliation happens automatically?
--snip--

Interesting. I guess you could do that, but I'm not sure why you'd want
to. Why are you taking the redundant disk off site? This smells a bit like
the old backup vs redundancy confusion. Any way, maybe LVM snapshots are
what you really want? They'll let you capture a whole, consistent
filesystem image while it's still in use.

It's not an un-common scenario. You satisfy the google requirement of 3 copies and 1 is off-site... LVM, while nice, just gets in the way and adds to the complication factor.

Gordon

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