On 8/15/2011 4:42 PM, NeilBrown wrote:
..I'm not sure from you description whether the following describes
exactly
what you are doing or not, but this is how I would do it.
As you say, you need two bitmaps.
So if there are 3 drives A, X, Y where A is permanent and X and Y are
rotated off-site,
then I create two RAID1s like this:
mdadm -C /dev/md0 -l1 -n2 --bitmap=internal /dev/A /dev/X
mdadm -C /dev/md1 -l1 -n2 --bitmap=internal /dev/md0 /dev/Y
mkfs /dev/md1; mount /dev/md1 ...
Then you can remove either or both of X and Y and which each is
re-added it will
recover just the blocks that it needs.
X from the bitmap of md0, Y from the bitmap of md1.
NeilBrown
How elegantly described.
After so many instances of being told "You should not use RAID as a
backup device like that!"
it is pleasant to hear you detail the "right way" to do this.
Thank you very much for that Neil.
--
Cheers,
Maurice Hilarius
eMail: /mhilarius@xxxxxxxxx/
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