“The fact that the ext2 file system has limitations is not a
secret. It is inefficient when dealing with large file system
sizes, it has a 2GB file limit, and relatively poor performance.
While for the average user this does not matter much, in the middle
and high-end server markets, this makes a big difference. In such
markets database sizes are often beyond 2GB, and multiple drive
arrays can make for file systems in the terabyte range. Performance
degrades as the drive size goes up, and large files are (of course)
slower to access….”
“So how does one get around these limitations? A better method
of accessing the disk is through the use of a “journaling,” a
technique that allows the drive to write the data to disk using
buffering. When a drive asks to modify a block, it modifies a copy
in the journal instead. Only after the journal copy is written to
the journal itself will the data be written to the disk. This
allows undoing of changes to the file system (the new data in the
journal can be overwritten), or recreation of the new data in case
something goes wrong (copying the journal data into place on the
drive). This technique offers better performance (data can be
written sequentially into the journal, then written to the disk
later) and better crash recovery.”
“Several projects are underway to develop a replacement for
the ext2 file system with the advantages of a journaling file
system. Three of them are highly notable, as they have been
developing rapidly to a usable state, and all use journaling. These
three are the ReiserFS Balanced Tree File System, the SGI XFS File
System and the Ext3 File System. Each of these file systems have
unique features and development paths, and could possibly be the
successor to the ext2 file system.”