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Thread: Ubuntu 13.04 To Look At XZ-Compressed Packages

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    Default Ubuntu 13.04 To Look At XZ-Compressed Packages

    Phoronix: Ubuntu 13.04 To Look At XZ-Compressed Packages

    Another interesting topic for the Ubuntu 13.04 Developer Summit later this month is about using XZ compression by default for its packages, which would lead to a reduction in file-size...

    http://www.phoronix.com/vr.php?view=MTIwNTk

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    That's a good thing for people like me with slow/limited internet. I also hope they adapt delta diff from fedora/rpm. That significantly improves update download.

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    Haha, "because Fedora"

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    Default Lzip

    Another (maybe better) option could be lzip but it was denied in debian, see http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=556960

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    Quote Originally Posted by oibaf View Post
    Another (maybe better) option could be lzip but it was denied in debian, see http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=556960
    I had not heard of lzip until now, however it is yet another compressor based upon lzma, just like xz, I don't know if there is any benefit with lzip compared to xz. Then there's lrzip (from Con Kolivas of brain-fuck scheduler fame) which combines a long range compressor with lzma.

    There is a discussion of perhaps using it (lrzip) for package compression on Arch Linux (which currently uses xz), but it's just a suggestion at this point and warrants further investigation.

    Switching from gzip to xz (or another lzma based compressor) seems like a no-brainer though, it compresses slower than gzip but that doesn't affect the end users, the compression is much better and the decompression speed is only slightly slower.

    When speaking of lzma which is what these compressors have in common (expect gzip) it should be noted that it originated in 7-zip which is a great free open source cross-platform archiver by Igor Pavlov.

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    Sure, XZ decompression may not hurt much on current machines, but it's still a huge hog for older ones.

    On 486-class hw, it takes over 10x as long to decompress vs gz, while also using 32x the RAM or more (depends on dictionary size). I've also had xz -9 OOM occasionally trying to compress a big tarball, the cpu + ram requirements for compression are just ridiculous (on a comp with 8gb ram no less).

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    Instead of going to XZ (or, maybe: alongside it) they should develop something like "delta rpm". for those who do not use Fedora/Suse systems: it allows you, during an update, to download only the difference ("delta") between the old package and the new one; on debian/ubuntu you have to download the whole new package.
    How much does it saves? Once, during update I've saved... 96% of broadband (i.e. instead of downloading 100mb of updates I had to download 4mb)! Sure- this one was exceptional; some stuff cannot be "delted" and have to be downloaded "as it is" (mostly: kernels), but still we are talking about ~70% savings.
    Ah, and the good thing is: you do not need to keep old rpms to compute deltas- you can easily do it from installed packages, so no need for keeping constantly groving /var/yum* directories...
    This is a something I would love to see in Ubuntu.

    ah, and the author of the article forgot to mention Slackware- AFAIK it was the first one who use XZ compressed packages.

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    Quote Originally Posted by curaga View Post
    On 486-class hw, it takes over 10x as long to decompress vs gz, while also using 32x the RAM or more (depends on dictionary size).
    That's bad news for my 486DX2 66MHz PC.... I guess when the move to xz takes place I'll have to buy a new PC or upgrade to a Pentium Overdrive!! Oh wait... this isn't 1997 anymore.

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    Quote Originally Posted by XorEaxEax View Post
    When speaking of lzma which is what these compressors have in common (expect gzip) it should be noted that it originated in 7-zip which is a great free open source cross-platform archiver by Igor Pavlov.
    This. The only question is: what took them so long?
    I've been using xz for a while. It's very useful when I have to move large log files over the network, for example. Just replace czf with cJf and you're done!

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    Quote Originally Posted by devius View Post
    That's bad news for my 486DX2 66MHz PC.... I guess when the move to xz takes place I'll have to buy a new PC or upgrade to a Pentium Overdrive!! Oh wait... this isn't 1997 anymore.
    This move does make sense for Ubuntu, since they don't even support Pentium M anymore.

    But it's more about Debian, I think they still support 486?

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