On Thu Jan 28, 2010 at 11:05:33AM -0500, Carlos Williams wrote:

Thanks all. Last question. If I have my system as 3 disks in RAID5
array and the 4th disk as a hot spare. Do I still need to format the
4th disk with a filesystem (ext4)? Or will that occur when the
software discovers a disaster in the RAID volume and then starts to
sync the 'hot spare' into the degraded array to take the place of the
failed drive?

The 4th disk does have a 'fd' (RAID) partition table created but no
file system. Just trying to understand how that would work...

No, you don't need a filesystem.  The recovery process will use the data
on the remaining disks to calculate what data was on the failed drive,
and write that to the spare.  This data will include the filesystem (or
parts thereof).

Cheers,
    Robin
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