Guy wrote:
I don't think plan b needs to be handled as stated. If a cable is loose,
the amount of data that needs to be written somewhere else could be vast.
At least as big as 1 disk!
agreed; any such "active" bad block replacement will only postpone the
problem. It will never be able to solve the problem absolutely reliable.
I also agree, that it makes the system more complex and may need some
manual intervention, too.
That brings me back to:
If the hard drive can't re-locate the bad block, then, accept that you have
had a failure.
completely true. Kick off the bad disk and rebuild a new one sound
easy and save. But it is not! Before/during rebuild, your raid system runs
unprotected in a very fragile state, even more fragile than a single
disk system without raid! Thus the additional spare blocks may help
to bridge over this phase more safely. Thus this is not an alternative
of replacing the bad disk; you will do that, definitely!
Instead it is just an addition.
If you are hanging on a rope on a cliff, and notice, that the rope
shows a defect, what will you do? Cut it off, before it breaks
completely! and while falling, you may inspect your backpack to
find a spare rope to use.....
Dieter.
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