> lzma is default comrpession in very good compression SW 7-zip, which is
> faster and have higher compression ratio then bzip2 or rar.
>From what I've seen, lzma/xz compression is slower than bzip2, but generally
provides higher compression ratios. Both are remarkably slower than gzip,
but again, provide higher compression ratios. Decompression results are
similar, except that lzma/xz tends to be faster to decompress than bzip2.
In general though, higher compression requires more processor time. There
are any number of comparisons out there on the web that make this same
argument, except with data. Here's one:
http://tukaani.org/lzma/benchmarks.html
That said, there are certainly situations where you have more processor time
than you do bandwidth, so adding xz compression as an option for rsync may
make sense. It should not be viewed, however, as a win/win situation for all
circumstances.
One of my favorite ways to highlight the differences in compression algorithms
is to change the compression setting on a ZFS volume while under high load
(100-200 megabytes/second). The difference in CPU load for LZJB vs. gzip-1 is
enormous.
--Kyle
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