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Btrfs vs. EXT4 vs. XFS vs. F2FS On Linux 3.10

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  • #21
    Originally posted by IsacDaavid View Post
    Off-topic: From a merely theoretical standpoint, is there any benefit in (losslessly) compressing truly random data?
    If it's "truly random" then there is no pattern, and can not be any way to compress it.

    However, most data on a computer is not truly random. Text files and executable files are generally highly compressible. So is uncompressed video, but if you've already used a lossy compressor like mp3/h264/etc., then it's tough to do much more to it.

    A proper compressing filesystem should be able to detect when the data is compressible and when it should be skipped, and allow you to automatically take advantage of the feature only when it's actually beneficial.

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    • #22
      Originally posted by smitty3268 View Post
      If it's "truly random" then there is no pattern, and can not be any way to compress it.

      However, most data on a computer is not truly random. Text files and executable files are generally highly compressible. So is uncompressed video, but if you've already used a lossy compressor like mp3/h264/etc., then it's tough to do much more to it.

      A proper compressing filesystem should be able to detect when the data is compressible and when it should be skipped, and allow you to automatically take advantage of the feature only when it's actually beneficial.
      Btrfs does if you just do compress=(algorithm), it auto skips photos, music, videos and anything else that it sees as not easily compressed. If you want it to try anyway then there's a different mount option for that.
      All opinions are my own not those of my employer if you know who they are.

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      • #23
        Originally posted by stan View Post
        So let me see... BTRFS is slower than EXT4 pretty much everywhere, sometimes MUCH slower. All the purported features of BTRFS that are supposed to make BTRFS better are pie-in-the-sky as far as I can tell. Has anyone actually used the BTRFS snapshot thing on their Linux Desktop? Is there even a GUI for it, something that can come close to Apple's Time Machine? From a Linux Desktop user's perspective, BTRFS is worthless right now, and development resources going into it are a waste.

        As for compression, I'm sorry, but I don't want to waste CPU and get latency because the underlying filesystem sucks at arranging data on the hard disk.
        Features that make btrfs better than Ext4...

        1) Built in compress
        2) deduplication is being worked on
        3) built in volume manager
        4) ability to detect even single-bit corruption
        5) integrity checking the ext4 can never even DREAM of getting.
        6) ssd optimizations
        7) snapshotting
        8) online resizing
        9) online defragging
        10) Almost all raid levels supported in filesystem

        The only one the is even REMOTELY "Pie in the sky" is dedup, and its in progress. As far as your comment about compression... if you have a modern CPU then the compression takes less an millisecond except for gigantic files, which would most likely be video files...which it auto-skips on compression anyway, so you're getting zero latency. Also the data takes up less space on disk (important for early SSD adopters like me who only have 128GB ssd's in their laptops), and can be written TO disk more quickly since more data can be fit into the buffer.

        The snapshotting feature doesn't have a GUI yet, no, but its tech is stable and its being used on Suse and Fedora to integrate into update managers (same way windows does updates: create a snapshot before the update, update, if it breaks then you roll back to that pre-update snapshot).

        Is Btrfs slower than Ext4? Possibly. Though I'm not even positive it IS since we all know Michael's tests dont measure real-world performance (writing zeros to files doesnt count) but I don't even feel it or notice it on my laptop and I did a re-install to switch over to btrfs. The development efforts DEFINITELY aren't a waste, and I am looking forward to the day that either Btrfs or Tux3 replace Ext4.

        Quite honestly Stan you just look like a troll at this point, and a really bad one at that.
        All opinions are my own not those of my employer if you know who they are.

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        • #24
          A lot of people worry about compression and the latency or CPU load that might come with it. However, one of the most CPU intensive workloads that I do is compiling very large projects(Chromium, Android, etc), these keep CPU usage pegged at 100% on all cores nearly the whole time yet it is faster with BTRFS compression than without. One caveat is that you need to use LZO rather than ZLIB. It is slightly faster with compression on my SSD and much faster if the compilation is done on a rotational hard disk.

          Originally posted by Ericg View Post
          Features that make btrfs better than Ext4...

          1) Built in compress
          2) deduplication is being worked on
          3) built in volume manager
          4) ability to detect even single-bit corruption
          5) integrity checking the ext4 can never even DREAM of getting.
          6) ssd optimizations
          7) snapshotting
          8) online resizing
          9) online defragging
          10) Almost all raid levels supported in filesystem

          The only one the is even REMOTELY "Pie in the sky" is dedup, and its in progress. As far as your comment about compression... if you have a modern CPU then the compression takes less an millisecond except for gigantic files, which would most likely be video files...which it auto-skips on compression anyway, so you're getting zero latency. Also the data takes up less space on disk (important for early SSD adopters like me who only have 128GB ssd's in their laptops), and can be written TO disk more quickly since more data can be fit into the buffer.

          The snapshotting feature doesn't have a GUI yet, no, but its tech is stable and its being used on Suse and Fedora to integrate into update managers (same way windows does updates: create a snapshot before the update, update, if it breaks then you roll back to that pre-update snapshot).

          Is Btrfs slower than Ext4? Possibly. Though I'm not even positive it IS since we all know Michael's tests dont measure real-world performance (writing zeros to files doesnt count) but I don't even feel it or notice it on my laptop and I did a re-install to switch over to btrfs. The development efforts DEFINITELY aren't a waste, and I am looking forward to the day that either Btrfs or Tux3 replace Ext4.

          Quite honestly Stan you just look like a troll at this point, and a really bad one at that.

          I don't think he's a troll. I think his view is actually the current popular consensus even if I disagree with it.

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          • #25
            I've been back on btrfs since the 3.8 Kernel, and don't think I'll be switching to anything else. It's fairly quick with the recent updates, and I use the snapshotting ALL the time.

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            • #26
              Originally posted by Ericg View Post
              True, wasn't thinking about the fact that he just does zero-filled files instead of random-filled
              in case of random filled file it would be better for brtfs WITHOUT compression!

              purely random data cannot be compressed.

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              • #27
                Originally posted by set135
                Just to note, I have been using btrfs as an alternate backup for my core system (about 80g) for over a year. I
                rsync to the partition and snapshot that twice a month. Currenly, using compression, the btrfs is upto 120g, and
                contains 38 snapshots named by date. I have already found this 'time machine' useful for recovering data. I also
                have another btrfs partition mostly full of large video files. This machine has been killed by brownouts many
                times. So far, everything is working well. I still use ext4 for most of my filesystems, but I consider btrfs worthy
                of consideration. Particularly if I was going to use raid or volume management. Oh, this is a Gentoo box, so that
                core filesystem changes *a lot*, so those 38 snapshots are not trivial.
                You might look into experimenting with send/receive using btrfs. I imagine it'd be way more efficient than using rsync

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                • #28
                  Originally posted by stan View Post
                  So let me see... BTRFS is slower than EXT4 pretty much everywhere, sometimes MUCH slower. All the purported features of BTRFS that are supposed to make BTRFS better are pie-in-the-sky as far as I can tell. Has anyone actually used the BTRFS snapshot thing on their Linux Desktop? Is there even a GUI for it, something that can come close to Apple's Time Machine? From a Linux Desktop user's perspective, BTRFS is worthless right now, and development resources going into it are a waste.
                  Are you serious? I can't live without snapshots. And yes, there is a GUI tool for snapshots, it's called Snapper. Though it needs YaST for its GUI; otherwise, it's a CLI utility. It also does automatic snapshotting and can show the differences between files in different snapshots.

                  Originally posted by set135
                  Oh, this is a Gentoo box, so that core filesystem changes *a lot*, so those 38 snapshots are not trivial.
                  About Gentoo, I made an ebuild for Snapper, it's currently on Sunrise. You probably could use it, makes creating snapshots super easy. On my Gentoo machine, I made a "bmerge" script that makes a pre-post snapshot for every emerge process, so you can very easily do a perfect unmerge that way.

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                  • #29
                    I've been reading many positive critics about btrfs for a couple years and how this promising filesystem is supposed to eventually replace ext4, but after all this time I must admit those benchmarks feel a bit daunting, specially the compilation and database ones. Do you think btrfs will ever get near the speed of ext4, or is it that all those fancy features come at a performance cost?

                    I'm also waiting for swap file support.

                    Comment


                    • #30
                      Originally posted by IsacDaavid View Post
                      I've been reading many positive critics about btrfs for a couple years and how this promising filesystem is supposed to eventually replace ext4, but after all this time I must admit those benchmarks feel a bit daunting, specially the compilation and database ones. Do you think btrfs will ever get near the speed of ext4, or is it that all those fancy features come at a performance cost?

                      I'm also waiting for swap file support.
                      I'm by no means a file system expert, but I think that certain types of writes will just always be slow with COW file systems. If you desable COW for certain tests in btrfs, you do see substantial speedups. I suppose if you were on top of a btrfs raid array, you would still have some redundancy there.

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