Am 05.03.2007 um 23:29 schrieb Neil Brown:
On Monday March 5, ralf@xxxxxxxx wrote:
Is it possible to mark a disk as "to be replaced by an existing
spare",
then migrate to the spare disk and kick the old disk _after_
migration
has been done? Or not even kick - but mark as new spare.
No, this is not possible yet.
It's a pity - this would be a cool feature. It would take a lot of
worrying out of RAID5 maintenance. Even when you have a backup it takes
hours over hours to rebuild data from it when you crash a big RAID.
Do you
know if such a thing is on a ToDo list somewhere?
You can get nearly all the way there by:
- add an internal bitmap.
[ ... ]
- disassemble the raid1
- re-add the new drive to the raid5
However that won't work as the superblock will be in the wrong place
on the new drive.
It wouldn't be hard to relocate the superblock, but there currently is
no code to do this.
There has been an idea in PM to initially create the RAID5 out of
RAID1's
with only one disk. For migration one could add a disk to one of the
RAID1's,
let it sync and fail out the old disk. The question left had been if
a RAID1
with only one disk would propagate read errors to the RAID5 above -
so that
the RAID5 is be able to rewrite this sector - or simply fail the single
drive left.
Best regards
Ralf Mueller
--
Van Roy's Law: -------------------------------------------------------
An unbreakable toy is useful for breaking other toys.
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