7 ms·

It looks like it takes quite some time till it is fully implemented. Why should we start using it right now instead of btrfs/zfs?

AlgorithmicTime 10y ago
I don't think anyone is suggesting you should.
aseipp 10y ago
You probably shouldn't. It's ready for adventurous testers, and is pretty stable, but unless you're willing to report bugs or hack on it, you can probably stay away. There are reasons to still want it, despite its newness; for example, the latest updates bring huge improvements in metadata efficiency (low metadata overhead -> more metadata in the cache -> larger working set). Someone on the IRC channel reported it's somewhere around 20x faster than most filesystems when it comes to "iterate millions of files recursively", blowing everything else out of the water. (This seems somewhat synthetic, and I'd say it mostly is -- but OTOH, "tons of files in a directory" being really slow is life, and has bitten me multiple times in a prior job). In general, improved metadata efficiency helps everywhere, though. For example, if you're doing backups on a really big filesystem recursively, you'll have to traverse the metadata inodes a lot to get e.g. last modified time. bcachefs will likely do awesome here in terms of performance. Another unique feature I recall is the fact it has very very good tail latency -- bcachefs almost never blocks on I/O unncessarily, so you do not get random 'lag spikes' when things like the page cache get flushed out (which may halt some other I/O ops). This makes the system feel much more consistent, in general. There's lots of good info in the architecture document and Patreon posts from Kent: http://bcachefs.org/Architecture/ http://bcachefs.org/Architecture/ https://www.patreon.com/bcachefs/posts https://www.patreon.com/bcachefs/posts
- h2hn 10y ago
  I spent the last week testing ext4/btrfs/zfs on Linux and I found that zfs is rather slow and btrfs has improved its performance a lot in the last years (I should refined the script a bit, upload some graphics and make a post). https://gist.github.com/liloman/d525131fab9b9a440140905921e9346a https://gist.github.com/liloman/d525131fab9b9a440140905921e9... I'll give it a try on bcachefs. :) The script needs a 512MB spare disk partition and some basic changes but the fundamental work is there.
- JdeBP 10y ago
  Do you have any similar thoughts about HAMMER (from DragonFly BSD)?

AlgorithmicTime 10y ago

I don't think anyone is suggesting you should.

aseipp 10y ago

You probably shouldn't. It's ready for adventurous testers, and is pretty stable, but unless you're willing to report bugs or hack on it, you can probably stay away. There are reasons to still want it, despite its newness; for example, the latest updates bring huge improvements in metadata efficiency (low metadata overhead -> more metadata in the cache -> larger working set). Someone on the IRC channel reported it's somewhere around 20x faster than most filesystems when it comes to "iterate millions of files recursively", blowing everything else out of the water. (This seems somewhat synthetic, and I'd say it mostly is -- but OTOH, "tons of files in a directory" being really slow is life, and has bitten me multiple times in a prior job). In general, improved metadata efficiency helps everywhere, though. For example, if you're doing backups on a really big filesystem recursively, you'll have to traverse the metadata inodes a lot to get e.g. last modified time. bcachefs will likely do awesome here in terms of performance. Another unique feature I recall is the fact it has very very good tail latency -- bcachefs almost never blocks on I/O unncessarily, so you do not get random 'lag spikes' when things like the page cache get flushed out (which may halt some other I/O ops). This makes the system feel much more consistent, in general. There's lots of good info in the architecture document and Patreon posts from Kent: http://bcachefs.org/Architecture/ http://bcachefs.org/Architecture/ https://www.patreon.com/bcachefs/posts https://www.patreon.com/bcachefs/posts

h2hn 10y ago
I spent the last week testing ext4/btrfs/zfs on Linux and I found that zfs is rather slow and btrfs has improved its performance a lot in the last years (I should refined the script a bit, upload some graphics and make a post). https://gist.github.com/liloman/d525131fab9b9a440140905921e9346a https://gist.github.com/liloman/d525131fab9b9a440140905921e9... I'll give it a try on bcachefs. :) The script needs a 512MB spare disk partition and some basic changes but the fundamental work is there.
JdeBP 10y ago
Do you have any similar thoughts about HAMMER (from DragonFly BSD)?