bionic (8) nilfs.8.gz

Provided by: nilfs-tools_2.2.6-1_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/