"It's difficult to write storage articles at this time
and not focus on the upcoming 2.6.30 kernel. Why? This kernel is
loaded with a number of new file systems -- some of which we've
already covered, like ext4 and btrfs. Another of the hot new file
systems that is in 2.6.30 is NILFS. This file system is definitely
one that you should be testing.
"NILFS2 (New Implementation of a Log-Structured File System
Version 2) is a very promising new log-structured file system that
has continuous snapshots and versioning of the entire file system.
This means that you can recover files that were deleted or
unintentionally modified as well as perform backups at any time
from a snapshot without a performance penalty normally associated
with creating snapshots. In addition, there is evidence that NILFS
has extremely good performance on SSD drives."