Appeal 2007-1951
Application 10/120,016
Action to write new data to the currently used location and coping the
old data to an unused disk location would counteract the storage
efficiencies that the Hitz system is meant to provide. As mentioned
above, Hitz specifically states that because WAFL always writes new
data to unused disk locations, the snapshot tree does not change even
though the active file system does.
(Brief. 12 – 13). Appellants provide further rationale to support this
argument on pages 3 through 13 of the Reply Brief.
The Examiner responds in the Answer, stating:
The Appellants make much of the fact that the Hitz reference
discloses that "Because WAFL always writes new data to unused disk
locations, the snapshot tree does not change even though the active
file system changes." (see col. 18, lines 30-32).
This fact, however, has nothing to do with the feature of the
Hitz invention that constitutes the improvement over the prior art, and
is in fact the principle of operation of the system. The improvement
and principle of operation has to do with the fact that each snapshot of
the Hitz system requires only a single inode to be created, and
thereafter requires the duplication of only those data blocks which
have been modified. This is in contrast to the prior art, where a
second copy of the entire inode file as well as copies of all indirect
blocks are required for the creation of a snapshot.
(Answer 8). Further, the Examiner finds that modifying Hitz with Siddha’s
copy-on-write scheme would not require substantial reconstruction.
(Answer 9). Additionally, the Examiner finds that the performance of either
method of copy-on-write scheme is exactly the same. (Answer 10).
Thus, the issue before us is whether it would have been obvious to
modify the system of Hitz such that in response to a write of new data to a
section of storage, the data existing in the section of storage is first copied to
another section of storage, and then the data written to the section of storage
as recited in the independent claims.
PRINCIPLES OF LAW
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Last modified: September 9, 2013