The most common Linux file-systems we talk about at Phoronix are of course Btrfs and EXT4 while the ZFS file-system, which is available on Linux as a FUSE (user-space) module or via a recent kernel module port, gets mentioned a fair amount too. When it comes to the FreeBSD and PC-BSD operating systems, ZFS is looked upon as the superior, next-generation option that is available to BSD users. However, with the DragonFlyBSD operating system there is another option: HAMMER. In this article we are seeing how the performance of this original creation within the DragonFlyBSD project competes with ZFS, UFS, EXT3, EXT4, and Btrfs.
HAMMER is a file-system created by the DragonFlyBSD developers themselves and is the default choice when installing this BSD operating system, but UFS remains a choice too. The one sentence description about this file-system is that "[HAMMER] provides instant crash recovery, multi-volume file systems, integrity checking, fine grained history/undo, networked mirroring, and historical snapshots." HAMMER uses no fsck, can be sized up to one Exabyte, supports up to 256 volumes of four petabytes in size, coarse-grained history provided by snapshots with up to sixty days history, live snapshot access, and data/meta-data is CRC-checked.
rest here