Am 18.06.2009 um 10:27 schrieb Goswin von Brederlow:
Ralf Müller <ralf@xxxxxxxx> writes:
After I added a forth 1.5TB disk to the array yesterday and
reshaped the
former 3 disk raid5 to a 4 disk one, I wiped out the 300GB disk
raid5,
set one of the 1.2TB partitions faulty, removed it from its raid,
removed the 300GB partition and resized the former 1.2TB partition
(in place) to 1.5TB. Now I added this partition to its raid.
It has been recognized as a former member of this raid - so far so
good - but for whatever reason the raid subsystem decided to start
a complete recovery.
So here my question:
What went wrong and what do I have to do to avoid a full recovery for
the next disk?
I guess something wrote to your raid5 while the one disk was
removed.
Thats possible - after re-add, the bitmap showed 2/275 pages as unclean.
When you added it back the event counter would differ and the
disk needs to be resynced completly. A bitmap would help limiting this
to the parts that have changed. Add an internal bitmap before you
remove the next disk.
There is an internal write intent bitmap at the array:
DatenGrab:/media # cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4] [raid1]
md3 : active raid5 sdf1[3] sdi1[0] sdj1[4] sdh1[1]
3457099008 blocks super 1.2 level 5, 256k chunk, algorithm 2
[4/4] [UUUU]
bitmap: 0/275 pages [0KB], 2048KB chunk
Do you have an idea why this bitmap has been ignored?
Alternatively stop the raid completly, resize all the partitions and
start the raid again. No need to fail/readd each disk in turn.
good idea ...
Thanks so far
Ralf
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