[throwaway270925]

This should be at the top, using metadata DUP on a 3 disk volume is already asking for it, and of course you loose data when you just use it as jbod with data stored only once. Unless this are enterprise disks with capacitors anything can happen when it suddenly looses power. Not the FSes fault.

With the same configuration this can happen with ZFS, bcachefs etc just as well.

[rcxdude]

Will it render the whole filesystem inaccessible and unrepairable on those filesystems as well? One of the issues with btrfs is that it's brittle: failure tends not to cause an inconsistency in the affected part of the filesystem but bring down the whole thing. In general people are a lot more understanding of a power failure resulting in data corruption around the files that are actively being written at the time (there are limits to how much consistency can be achieved here anyway), much less so when the blast radius expands a lot further.

[adrian_b]

A few decades ago, XFS was notorious because a power failure would wipe out various files, even if they had been opened only for reading. For instance, I had seen many systems that were bricked because XFS wiped out /etc/fstab after a power failure.

Nevertheless, many, many years ago, the XFS problems have been removed and today it is very robust.

During the last few years, I have seen a great number of power failures on some computers without a UPS, where XFS was used intensively at the moment of the power failure. Despite that, in none of those cases there was any filesystem corruption whatsoever, but the worst that has ever happened was the loss of the last writes performed immediately before the power failure.

This is the behavior that is expected from any file system that claims to be journaled, even in the past many journaled file systems failed to keep their promises, e.g. a few decades ago I had seen corrupted file systems on all existing Linux file systems and also on NTFS. At that time only the FreeBSD UFS with "soft updates" was completely unaffected by any kind of power failures.

However, nowadays I would expect all these file systems to be much more mature and to have fixed any bugs long ago.

BTRFS appears to be the exception, as the stories about corruption events do not seem to diminish in time.

[theamk]

> Unless this are enterprise disks with capacitors anything can happen when it suddenly looses power. Not the FSes fault.

Most filesystems just get a few files/directories damaged though. ZFS is famous for handling totally crazy things like broken hardware which damages data in-transit. ext4 has no checksum, but at least fsck will drop things into lost+found directory.

The "making all data inaccessible" part is pretty unique to btrfs, and lets not pretend nothing can be done about this.