Btrfs Brings Some Great Performance Improvements With Linux 6.1

[fitzie]

I defragmented it after spending 23 hours. I won by 6 seconds. But 14 seconds is also a lot.

The block group tree work in 6.1 will bring it down to a few seconds. You will have to have to convert the filesystem to this new format, but since this is just moving block group objects out of the extent tree and into their own tree and not any other significant changes it should be relatively bug free. Of course, I would probably wait until at least 6.1.5 before trying it out.

[fitzie]

Hmm, that's interesting. Unfortunately, I can't test that for myself as I don't have a disk more than 1.1T in size. Out of curiosity I tried searching, and found just two mentions of such problem, on a Debian ML and on reddit. Neither has a link to a bugreport or to some comment by an actual BTRFS dev, so 🤷.

So, anyway, what I'd recommend in this situation is:

1. I don't know what kernel version you're using, but try latest stable one to see if that maybe a resolved issue
2. Try asking about that in btrfs IRC channel on libera server. From my experience of asking a few questions there over multiple years (well, the server was Freenode before, now it's Libera), there are actual devs hanging out, so they may give you a useful comment on the issue.
3. Try reporting a bug. In my book it is a situation that well deserves a bugreport, as nobody would want to wait additional 20 seconds while booting their laptop/desktop.

my 60TB filesystem takes three and a half minutes to mount.

This is a well understood issue, and it is part of the extent-tree-v2 work, that has recently been separated and coming to 6.1.x

see: https://lore.kernel.org/linux-btrfs/[email protected]/

[guglovich]

The block group tree work in 6.1 will bring it down to a few seconds. You will have to have to convert the filesystem to this new format, but since this is just moving block group objects out of the extent tree and into their own tree and not any other significant changes it should be relatively bug free. Of course, I would probably wait until at least 6.1.5 before trying it out.

I updated to 6.1.5 today, but nothing has changed for BTRFS.

[Hi-Angel]

I updated to 6.1.5 today, but nothing has changed for BTRFS.

Try do add a mount option `block_group_tree`. I'm not completely sure it's correct, but judging from the commit it looks is.

[fitzie]

Try do add a mount option `block_group_tree`. I'm not completely sure it's correct, but judging from the commit it looks is.

you'll also need btrfs-progs built with EXPERIMENTAL option, certainly if you are attempting to use it with an existing filesystem.
https://www.spinics.net/lists/linux-...msg128690.html