Appeal No. 2006-1540
Application No. 10/113,338
compacted state since the last stripe updated is known, i.e., the
data that used to be on the failed disk up to the last stripe
updated maybe rebuilt to spare units distributed among the
remaining disks in the disk array, thereby allowing the disk
array to enter a compacted state. It is this persistent tracking
of each stripe updated during expansion that is time consuming
and expensive (due to the cost of non-volatile memory). Thus,
appellants’ improvement over this conventional expansion process
is to eliminate the necessity of tracking the stripes updated
during expansion in order to enter a compacted state upon a
failure of the updated disk during expansion.
This improvement, recited in various ways in each of the
claims on appeal, is achieved by the mirroring step or apparatus
recited in each of the claims on appeal, in combination with
other steps or elements. In claim 1, for example: “mirroring said
data to a stripe unit that corresponds to said particular stripe
unit in a same stripe if said particular stripe unit was rebuilt
during said expansion process, wherein said mirror stripe unit is
located in another disk of said disk array” is recited.
It does appear that there is some “mirroring” occurring in
Ohizumi in that data is written to both a new disk and a spare
disk (see element S05 in Figure 7), but this does not seem to be
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