On 2/10/2010 10:36 AM, Sean M Clark wrote: > On 2010Feb10 8:50 AM, Steve Polyack wrote: > >> On 2/10/2010 8:16 AM, Petar Bogdanovic wrote: >> >>>> I want use bzip2 to compress my file, because I thing bzip2 is more >>>> efficient... >>>> >>>> >>> Really? >>> > [...] > >>> 255526 bytes less while six times slower.. >>> >>> >> This is extremely dependent on the contents of foo.iso. I don't think >> its a good test because you are only seeing 10% compression either way. >> There is a good chance that much of the data within your ISO is already >> compressed. When using data which is typically more compressible (text >> and other data that is not already compressed), the resulting size of >> something compressed with bzip2 can be much smaller than when compressed >> using gzip. It's true that it is much slower, but if he's talking about >> it being more efficient in terms of disk space used, then he is correct. >> > xz/lzma is another consideration. At moderate compression levels, lzma > seems to be about the same or slightly faster than bzip2 with a little > better compression. At lower compression levels it seems like it's > about as fast as gzip while compressing noticeably farther - at least > in the small amount of testing I've done so far with the "xz" > implementation of lzma compression. > > (The small amount of testing I've done so far suggests to me that xz > with a compression level of 1 runs about as fast as gzip4 with > compression at or better than gzip7, approaching bzip2 for some types of > files. Cranking up to xz 6 or 7 runs a bit faster than bzip2 default > but tends to give better compression.) > > On the other side of the spectrum, LZO/LZO2 compression is available which greatly favors compression speed while still providing a decent compression ratio. I'd like to see these algorithms make their way into Bacula, but their doesn't seem to be much interest in doing so. I suppose its understandable, as GZIP is fairly flexible.
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