>>>>> "Greg" == Greg Oster <oster@cs.usask.ca> writes:

    Greg> Well... if you have hot-swap drives, then you could just
    Greg> stuff the new drive in place of the old one, and not worry
    Greg> about doing a copyback.. (i.e. the new drive you put in
    Greg> becomes the hot spare).
    >> 
    >> Hmm, how to come!? The old/new drive still has state 'failed',
    >> the spare is 'used_spare'. So, what will happen if another
    >> drive fails in this stage?

    Greg> You stuff another drive into the box, hot-add it, and
    Greg> rebuild to it :)

Let's proceed: ;-)

I just can place in a new drive in place of a failed one. -> A known,
but 'failed' scsi id / /dev/sd.. refers to a fresh drive now. ->
Adding this as a new spare ('raidctl -a /dev/sd..', I guess) would
work!? (I wouldn't even dare...)

    >> How will the 'failed' drive become the new spare _without_
    >> reboot?

    Greg> You stuff a fresh drive into that slot, and when a different
    Greg> drive fails, rebuild to the fresh drive. Not quite the same
    Greg> as a spare, but works much the same. :)

But then you've lost the real spare / redundancy effect, because then
the first reconstruction step (onto the spare drive), normally done
automatically, has to be done manually, now.

-> Then it would be better to handle the complete spare drives
manually, because there are only smooth reconstructions. Having a
'used_spare' means either blocking copyback or a (reordering) reboot.

Or is 'raidctl -C ...' allowed with a used running raid!? (Another
thing I wouldn't dare! ;-))

Markus.