mklost+found — create a lost+found directory on a mounted Linux second extended file system
mklost+found is used to create a lost+found directory in the current working directory on a Linux second extended file system. There is normally a lost+found directory in the root directory of each filesystem.
mklost+found pre-allocates disk blocks to the lost+found directory so that when e2fsck(8) is being run to recover a filesystem, it does not need to allocate blocks in the filesystem to store a large number of unlinked files. This ensures that e2fsck will not have to allocate data blocks in the filesystem during recovery.
There are none.
There are none :-)
mklost+found is part of the e2fsprogs package and is available from http://e2fsprogs.sourceforge.net.