ideas

create raid tool at linux

On Speeding up RAID5 Reconfiguration

Pass 1:
if we're adding disks
	for each new disk
		for each block
			if it's not a parity block
				convert it to a global block # & wish for it

Pass 2:
for each block not yet wished for
	wish for it


In general:
	The routine that attempts to find a large contiguous read for each 
disk needs work.  When adding wished-for blocks, we need a way to determine
if block N-1 or N+1 is already present.  A bit-map could work for this.
Later, when we're looking for the largest contiguous stretch, we need the
lengths of each run.  Again, using a bit-map, a single pass through the map
could give us the beginning block # and length.  Sorting that, we just step
through the resulting array, reading/writing the runs.  We also need to clear
the bits as they're processed, in preperation for the next pass.