mesrik

  "134 UNIX System Administration Handbook
  ...
  The lost+found directory is automatically created when you build a filesystem. It is 
  used by fsck in emergencies; do not delete it. The lost+found directory has some
  extra space prealocated so that fsck can store "unlinked" files there without having
  to allocate additional directory entries on an unstable filesystem. Some systems pro-
  vide mklost+found command that can recreate this special directory if it is aci- 
  dentally deleted.
  ...
  "

  "52 UNIX FOR SUPER-USERS
  ...
  The filestore consistency check is performed by the command fsck (usu-
  ally stored as /etc/fsck, but sometimes in /bin), which should be used to check
  all discs used as file-systems. It defaults to the list of filestore devices given
  in the file /etc/checklist. At this stage, most of the file-systems will not be
  mounted, so will be inactive; only the root file-system will be active. The
  fsck command goes through each one in turn, reports any inconsistencies in
  them, and offers to correct them. The reply to each query is either 'y' for yes
  (correct the inconsistency), or 'n' for no (leave the file-system inconsistent).
  A parameter '-y' to the command assumes 'yes' replies to all questions, so
  that no further interaction is necessary; a parameter '-n' similarly assumes
  all 'no' answers, and therefore needs no write permission to the device. Any
  'yes' reply may involve the loss of information, such as the complete removal
  of a suspect file. Suspect files on the file-system being checked are written to
  a directory lost + found on the device if such a directory exists; this directory
  must have been created, and be sufficiently large already to hold the names
  of all the files involved. This can be ensured by first creating the directory,
  then creating a number of files in the directory, and then removing them.
  The corrected systems will be consistent, and can later be mounted as and
  when required. It may be possible to recover information from deleted files
  by looking at the lost + found directory. There should be a lost + found direc-
  tory at the head of each mountable file-system.
  When checking the root file-system, there are complications, in that it
  will be active (even though, because it is root, it will not be formally mounted
  as such, but is implicitly mounted as root during the booting process). If
  modifications are necessary, they should be completed, and the machine
  rebooted without first performing a sync (see section 4.5 below for the nor-
  mal procedure for taking a system down). This is to ensure that the disc as
  modified by fsck is not overwritten by any in-core information, which may
  have been generated from information read from the original corrupt (incon-
  sistent) version.
  ...
  "