On 17.06.2010 15:37, super master wrote: > Hello, > many linux SW is starting to implement new lzma compresson instrad of old > zlib (gzip) od bzip2. > > lzma is default comrpession in very good compression SW 7-zip, which is > faster and have higher compression ratio then bzip2 or rar. > > Currently its probalby the best compressor in therms of compression and > decompression speed / compression ratio. > > In linux there is GNU lzma SW which implements lzma algorithm. > > In my optinion it would be very useful if rsync could use this compressor > optionaly as upgrade of old zlib. > > more info: > http://en.wikipedia.org/wiki/Lempel%E2%80%93Ziv%E2%80%93Markov_chain_algorithm
lzma draws most of it's strength from using a much larger "Working Window" (megabyte to gigabyte, instead of a few kilobyte like gzip). AFAIU rsync works with blocks in the kilobyte-range, which effectivly prevents lzma from using it's main strength. For illustration i've just tried "xz -0" on a linux-kernel tar-ball. "xz -0" still uses a much larger window that gzip! The man-page says about 6 megabytes and the man-page reserves a future change to an algorithm other than lzma. On said linux-kernel tar-ball the compression was only slightly better that gzip. 87634801 byte for gzip with defaults 86841598 byte for gzip -9 85544824 byte for xz -0 For comparison: 55044372 byte for xz -e9 Bis denn -- Real Programmers consider "what you see is what you get" to be just as bad a concept in Text Editors as it is in women. No, the Real Programmer wants a "you asked for it, you got it" text editor -- complicated, cryptic, powerful, unforgiving, dangerous. -- Please use reply-all for most replies to avoid omitting the mailing list. To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
