Per default it's made automatically every 20th sync, which can be a right drag if you have big drives... IIRC Hijack turns this behaviour off, but the drives will still get fsck'ed (unix style scandisk) in case something bad happens.

There's no need to run stuff like defrag since the ext2 file system is good about keeping itself non fragmented (and there's comparatively very little activity on the file systems on the empeg - consider how trashed on a partition with a news spool gets on a normal system - and they still remain within sane numbers for fragmantation)

/Michael