Appeal No. 2006-1540
Application No. 10/113,338
in the disk array. As explained by appellants in the background
section of the specification, the process of reconstructing the
data contained on the failed disk and copying it onto the spare
unit of each stripe is called “compaction,” because the RAID is
in a “compacted” state due to the number of active disks in the
disk array being decreased by one.
The background section of the specification goes on to
explain that once the failed disk is either repaired or replaced
by a spare disk, the data on the failed disk may be restored by
copying back the spare unit data onto the corresponding stripe
units in the repaired or spare disk stripe by stripe, and that
this process of copying back the spare unit data onto the
repaired or spare disk stripe by stripe is referred to as
“expansion.”
Then, the background section of the specification explains
the problem with the prior art. During the expansion process,
each stripe that is updated, i.e., each stripe unit per stripe
that is rebuilt in the repaired or spare disk, may be tracked.
But there could be a failure during the expansion process and
because of this possibility, each stripe updated during the
expansion process is tracked. If the repaired or spare disk
fails during the expansion process, RAID is able to enter a
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