Provided by: nilfs-tools_2.2.7-1_amd64 bug

NAME

       NILFS - the new implementation of a log-structured file system

SYNOPSIS

       Overview of the NILFS file system and the related tools.

DESCRIPTION

       NILFS  is  a  log-structured  file  system developed for Linux.  NILFS provides versioning
       capability of an entire file system and  continuous  snapshotting  that  allows  users  to
       restore files mistakenly overwritten or destroyed a while ago.

       The  current  major version of NILFS is version 2, which is referred to as NILFS2.  NILFS2
       is equipped with an online garbage collector (also  called  cleaner)  that  reclaims  disk
       space in the background with keeping multiple snapshots.

       When  data  is  written  or  any  change is made to a NILFS2 file system, it automatically
       creates a checkpoint.  A checkpoint represents a  consistent  state  of  the  NILFS2  file
       system of a certain instant.  It becomes mountable after being changed into a snapshot.  A
       snapshot is the checkpoint marked not to be deleted by  the  cleaner.   NILFS2  creates  a
       number of checkpoints at regular intervals (unless there is no change) or with synchronous
       writings.  There is no practical limit on the number of checkpoints and snapshots.

       The following tools are available to manage the checkpoint and the snapshot:

       lscp        lists checkpoints or snapshots

       mkcp        makes a checkpoint or a snapshot

       chcp        changes an existing checkpoint to a snapshot or vice versa

       rmcp        invalidates specified checkpoint(s)

       These tools give the versioning capability  to  NILFS2;  a  user  can  select  significant
       versions  among  continuously  created  checkpoints and can change them to snapshots to be
       preserved for long periods.

       Every checkpoint except for the snapshot will become unprotected from the cleaner after  a
       given  period  of  time.   This  period  is  controlled by the protection_period parameter
       defined in the /etc/nilfs_cleanerd.conf(5) file.

MOUNT OPTIONS

       Refer to the mount.nilfs2(8).

EXAMPLES

       mkfs -t nilfs2 /dev/sdb1
              creates a NILFS2 file system on a block device `/dev/sdb1'.

       mount -t nilfs2 /dev/sdb1 /nilfs
              mounts the NILFS2 file system on a mount point `/nilfs' like an ordinary POSIX file
              system.   This  will invoke a cleaner process nilfs_cleanerd(8) through an external
              mount program (i.e. mount.nilfs2(8)).

       lscp   lists checkpoints created in the file system as follows:

               CNO        DATE     TIME  MODE  FLG      BLKCNT       ICNT
                 1  2014-01-18 20:49:54   cp    -            4          2
                 2  2014-01-18 20:51:45   cp    -         3990         11
                 3  2014-01-18 20:51:45   cp    -         6058          3
                 4  2014-01-18 20:51:49   cp    -         4807          6
                 5  2014-01-18 20:51:49   cp    -          262          3
               ...

       chcp ss 2
              changes the checkpoint whose checkpoint-number is two  to  a  snapshot.   Then  the
              checkpoint list will become as follows:

               CNO        DATE     TIME  MODE  FLG      BLKCNT       ICNT
                 1  2014-01-18 20:49:54   cp    -            4          2
                 2  2014-01-18 20:51:45   ss    -         3990         11
                 3  2014-01-18 20:51:45   cp    -         6058          3
                 4  2014-01-18 20:51:49   cp    -         4807          6
                 5  2014-01-18 20:51:49   cp    -          262          3
               ...

       mount -t nilfs2 -r -o cp=2 /dev/sdb1 /snapshot
              mounts  the  snapshot  on another directory `/snapshot' as a read-only file system.
              Here the snapshot mount requires at least two options, a read-only option (-r or -o
              ro)  and the cp option (-o cp=checkpoint-number).  Note that a read/write mount and
              one or more snapshots are mountable independently, so the online backup is possible
              through the snapshot mounts.

               # mount -t nilfs2
               /dev/sdb1 on /nilfs type nilfs2 (rw,gcpid=13296)
               /dev/sdb1 on /snapshot type nilfs2 (ro,cp=2)

       umount /nilfs
              unmounts  the  NILFS2  file  system  mounted  on  `/nilfs'  and  will  shutdown the
              nilfs_cleanerd(8) through an external umount  program  (umount.nilfs2(8))  for  the
              read/write mount.

AUTHORS

       NILFS2 was developed by NILFS development team.

SEE ALSO

       mkfs.nilfs2(8),        mount.nilfs2(8),        umount.nilfs2(8),        nilfs_cleanerd(8),
       nilfs_cleanerd.conf(5), nilfs-tune(8), nilfs-clean(8), nilfs-resize(8), lscp(1),  mkcp(8),
       chcp(8), rmcp(8), lssu(1), dumpseg(8)

       http://nilfs.sourceforge.net/