DragonFlyBSD 5.0 is the first release with preliminary boot support for HAMMER2, the project’s new filesystem.
Preliminary HAMMER2 support has been released into the wild as-of the 5.0 release. This support is considered EXPERIMENTAL and should generally not yet be used for production machines and important data. The boot loader will support both UFS and HAMMER2 /boot. The installer will still use a UFS /boot even for a HAMMER2 installation because the /boot partition is typically very small and HAMMER2, like HAMMER1, does not instantly free space when files are deleted or replaced.