Improved Btrfs Scrub Code Readied For Linux 6.4, ~10% Faster

[caligula]

I suspect its a comment made in jest. In my experience, Btrfs works really well, both on my private systems and on servers at work.

Yes, but the scrub has been around 50% slower than ZFS. So.. it takes ages with larger arrays of 60+ TB.

[S.Pam]

Yes, but the scrub has been around 50% slower than ZFS. So.. it takes ages with larger arrays of 60+ TB.

How so? Are you perhaps trying to scrub a RAID56 filesystem?

[guglovich]

A drop in the sea. We need to work towards fast partition mounting.

[cynic]

A drop in the sea. We need to work towards fast partition mounting.

they're working on it. Extent tree v2 should solve the issue, but it won't come too soon.

[waxhead]

A drop in the sea. We need to work towards fast partition mounting.

Already solved with the block tree feature.

[caligula]

How so? Are you perhaps trying to scrub a RAID56 filesystem?

Yeah, it's a waste of space to use RAID1 in a home NAS.

[zxy_thf]

Perhaps, but can you convert from one to another, and will people actually do that? If not there will still be a lot of old filesystems around.

It's not a huge trouble since hard drives have lifespans
I "converted" my XFS volumes to btrfs when replacing my old hard drive, due to lack of data checksum, and I'm planning to change the default hashing algorithm to xxhash when replacing my current btrfs volumes, which will happen a few years from now.

[fitzie]

Already solved with the block tree feature.

yes, you need to compile btrfs userspace with an enable-experimental flag to create/convert btrfs filesystems. I did that, and it took my 50+TB filesystem mount from 4 minutes to a few seconds. Btrfs is pretty good these days.

[geearf]

yes, you need to compile btrfs userspace with an enable-experimental flag to create/convert btrfs filesystems. I did that, and it took my 50+TB filesystem mount from 4 minutes to a few seconds. Btrfs is pretty good these days.

Oh wow, maybe I won't need to use bcache to speed mounting time anymore.

[S.Pam]

Yeah, it's a waste of space to use RAID1 in a home NAS.

Then I suggest you scrub each drive individually instead of the whole filesystem. It is an unfortunate 'bug', as when you scrub the filesystem, btrfs will initiate a scrub on each device in parallel, but with striped profile, it needs to read all stripes, which are on the other drives. This will cause a massive slowdown, especially on rotating disks. The solution is to scrub one device at the time.