A new file system,
ext4, is based on and upwardly compatible with ext3.
Ext4 WikiExt4 Development ProjectExt4 on WikipediaHere is
an interview with Eric Sandeen in which he discusses the features and timetable of ext4.
Tidbits:
Upwardly compatible: An ext3 file system can be mounted as ext4. Once it has been modified, it can no longer be mounted as ext3.
Faster performance, due mostly to a new on-disk extent format.
Allows for larger file systems (up to 1024P*) and larger files (16T**)
* P as in Petabyte = 1000 Terabytes.
** T as in Terabyte = 1000 Gigabytes
Current ext3 capacities are 16T for filesystems and 2T for files.
Larger max limit for number of subdirectories (65k)
"Persistent preallocation"
nanosecond resolution on timestamps
An online defragmentation utility
Ext4 will be available in Fedora 9, but will not be the default.
