[ Thanks to dave for
this link. ]
“After an unexpected power failure or system crash (also called
an unclean system shutdown), each mounted ext2 file system on the
machine must be checked for consistency by the e2fsck program. This
is a time-consuming process that can delay system boot time
significantly, especially with large volumes containing a large
number of files. During this time, any data on the volumes is
unreachable.“The journaling provided by the ext3 file system means that this
sort of file system check is no longer necessary after an unclean
system shutdown…”