Donovan Baarda abo at minkirri.apana.org.au
Mon May 3 09:39:32 GMT 2004


From: "Mike McCallister" <mikemc-rsync at contactdesigns.com>
> http://rsync.samba.org/ftp/unpacked/rsync/patches/gzip-rsyncable.diff
> Since the patch was created a while ago and is not part of the default
> gzip yet, I was wondering if rsync users on this list had any opinions
> on the patch regarding its effectiveness and/or any problems it may
> cause with gzip.  Is this patch the way to go, or am I better off trying
> out a different compression algorithm (not gzip related) altogether?

I don't know how cleanly the patch will apply to recent gzip's, but it
should be OK as gzip itself seems to be pretty stable these days.

I do know how it works. After posting my firm opinion that it was not
possible, I was proven wrong. The idea it uses is very clever and highly
effective. It will have a negative impact on the compression because it
resets the compressor at semi-regular intervals. It will also miss some
matches that you would get on uncompressed data as it requires a slightly
longer run of "match" data to re-syncronise.

However, the compression losses and missed matches are reported to be
minimal. I'd say it is worth trying.

Donovan Baarda                http://minkirri.apana.org.au/~abo/

More information about the rsync mailing list