"Mike Snitzer" <snitzer@xxxxxxxxx> writes:
> All,
>
> I have repeatedly seen that when a 2 member raid1 becomes degraded,
> and IO continues to the lone good member, that if the array is then
> stopped and reassembled you get:
>
> md: bind<nbd0>
> md: bind<sdc>
> md: kicking non-fresh nbd0 from array!
> md: unbind<nbd0>
> md: export_rdev(nbd0)
> raid1: raid set md0 active with 1 out of 2 mirrors
>
> I'm not seeing how one can avoid assembling such an array in 2 passes:
> 1) assemble array with both members
> 2) if a member was deemed "non-fresh" re-add that member; whereby
> triggering recovery.
>
> So why does MD kick non-fresh members out on assemble when its
> perfectly capable of recovering the "non-fresh" member? Looking at
> md.c it is fairly clear there isn't a way to avoid this 2-step
> procedure.
>
> Why/how does MD benefit from this "kicking non-fresh" semantic?
> Should MD/mdadm be made optionally tolerant of such non-fresh members
> during assembly?
>
> Mike
What if the disk has lots of bad blocks, just not where the meta data
is? On every restart you would resync and fail.
Or what if you removed a mirror to keep a snapshot of a previous
state? If it auto resyncs you loose that snapshot.
MfG
Goswin
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