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Comment by ThatPlayer | Hacker News Reader

I believe openSUSE uses Btrfs.

I haven't lost data on it, but my 8 drive Btrfs RAID6 filesystem locked up read-only on me, which wasn't fun. Switched to ZFS after that.

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I have had single-drive btrfs filesystems lock up on me twice; i.e. file manipulation commands like `ls` freeze and "take forever". In both cases, there was a hardware failure of the drive. I believe that the frozen processes went into uninterruptible sleep (so they couldn't be killed).

It is totally understandable that if the underlying driver starts returning errors, btrfs (or any other filesystem) may be unable to provide access to my data; but I was not at all happy about having to reboot the entire machine.

(I must admit, it is possible that the "freezing" was happening in underlying block device driver code and not in btrfs. I don't remember if I ever checked wchan to see which it was. My impression from reading dmesg output was the issue seemed to be with btrfs.)

I did once have a similar experience with ZFS as well. Sigh.

Couple weeks ago had someone complain about system updates and other mildly IO heavy things making his system extremely slow and lock up for minutes at a time, despite having an NVMe SSD. Rebalancing fixed it - which iirc I also had to do regularly about ten years ago when I had the exact same problems with btrfs.

Yeah, OpenSUSE does BTRFS although they also support XFS. I ran tumbleweed for a while and managed to lose a root filesystem twice, although that was a few years ago and appeared to be triggered by running out of space, as the home filesystem on the same box, also BTRFS, survived both times.

RAID5/6 is still quite beta in btrfs. mdadm+btrfs is the way to go here.

Actually any RAID is beta in btrfs, but configurations with one storage device (e.g. firmware of Turris Omnia) do quite well on prod.

No, it's not beta. You can check the status here https://btrfs.readthedocs.io/en/latest/Status.html

Only raid5/6 has known issues.

This was also about 8 years ago. It was originally a RAID1 setup, but I did an in-place converter to RAID6, which is cool. And like I said, I didn't lose any data.

With mdadm, I don't get auto-repair on top of the checksumming.

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