Btrfs Gets A Big Improvement For More Robust RAID1 In Linux 5.5

David Sterba sent in his pull request early of the Btrfs file-system changes that are ready for merging into the Linux 5.5 merge window next week.

The biggest improvement is the Btrfs native RAID support now supporting three and four copy options for RAID1. Btrfs' RAID1 code up to now has always relied upon two copies of data while now there is support for three and four copies if desired for better data integrity. This new "RAID1C3" mode is intended as a replacement of RAID6 profile on meta-data and more resiliency against the possible failure of two drives in an array.

Besides adding this new backwards-incompatible RAID1C3/RAID1C4 modes, Btrfs in Linux 5.5 also has new checksum capabilities around per-file-system, faster hashing with xxhash, faster LSEEK that can speed up some operations by 80%, the Btrfs SEND code now allows clone operations within the same file, and a variety of code clean-ups. Various bugs have also been fixed in this code for the next Linux kernel.

The complete list of Btrfs changes queued for Linux 5.5 can be found via this pull request.