Reducing SquashFS delta size through partial decompression  In
a previous article titled ‘using deltas to speed up SquashFS
ebuild repository updates’, the author has considered benefits
of using binary deltas to update SquashFS images. The proposed
method has proven very efficient in terms of disk I/O, memory
and CPU time use. However, the relatively large size of deltas
made network bandwidth a bottleneck.  The rough estimations done
at the time proved that this is not a major issue for a common
client with a moderate-bandwidth link such as ADSL.
Nevertheless, the size is an inconvenience both to clients
and to mirror providers. Assuming that there is an upper bound
on disk space consumed by snapshots, the extra size reduces
the number of snapshots stored on mirrors, and therefore
shortens the supported update period.  The most likely cause for
the excessive delta size is the complexity of correlation
between input and compressed output. Changes in input files are
likely to cause much larger changes in the 