Blog/Btrfs-progs v5.15 released

From Forza's ramblings

2021-11-07: Btrfs-progs v5.15 was released with several new defaults!

Btrfs-progs v5.15 was just released to match the release of the new Linux Kernel 5.15. It is very exciting because it has changed many defaults to match the requirements of a modern system.

The tree main things are in mkfs.btrfs:

  • no-holes is enabled by default
  • free-space-tree instead of space cache as default.
  • DUP is now always used for metadata on single devices.

No-holes is an improved representation of file extents where holes are not explicitly stored as an extent. This saves a few percent of metadata if sparse files are used.

free-space-tree is an improved Space Cache that has much better performance, especially on larger filesystems. An explanation and a guide on how to switch to the new Free Space Tree is over at Btrfs/Space_Cache.

DUP profile for metadata improves the reliability of the filesystem. The earlier defaults had SINGLE profile as default for metadata on non-rotational drives such as NVME and SSD. However, if there were some minor corruption in the metadata, it could lead to a damaged filesystem. With DUP metadata, Btrfs can self-heal from many corruptions in the metadata, keeping your filesystem in a healthy state.