"Before we begin, here is a quick summary of these
three new file-systems. EXT4 is the successor to EXT3 and this
file-system can now support volumes up to 1 Exabyte, introduces
Extents to replace traditional block mapping, supports persistent
pre-allocation and delayed allocation for improving performance,
brings journal check-summing to the EXT family, and file-system
checking is faster under EXT4. Previously we delivered real-world
benchmarks of EXT4 and found it to be a nice performance step above
EXT3 in a majority of the tests. Install-time support for EXT4 was
introduced with Ubuntu 9.04. EXT3 has been in the Linux kernel
since 2001 and is what a majority of the Linux desktop
distributions had been using as the default file-system.
"The Btrfs file-system has yet to be stabilized and is currently
at version 0.19 with its on-disk format not yet being finalized.
Btrfs supports online defragmentation, an SSD optimized mode,
copy-on-write logging, zlib compression, object-level mirroring and
stripping, sub-volumes, and writable snapshots. A few months back
we delivered Btrfs benchmarks with support for this file-system now
being available through Red Hat's Anaconda installer in Fedora 11.
These benchmarks found Btrfs to perform well in some areas, but
there's a lot left to be desired."