nilfs man page on Archlinux

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NILFS(8)							      NILFS(8)

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

       Overview of the NILFS file system and the related tools.

       NILFS  is a log-structured file system developed for Linux.  NILFS pro‐
       vides 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  consis‐
       tent  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 num‐
       ber of checkpoints and snapshots.

       The following tools are available to  manage  the  checkpoint  and  the

       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_clean‐
       erd.conf(5) file.

       Refer to the mount.nilfs2(8).

       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.

       lscp   lists checkpoints created in the file system as follows:

		 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 snap‐
	      shot.  Then the checkpoint list will become as follows:

		 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  pro‐
	      gram (umount.nilfs2(8)) for the read/write mount.

       NILFS2 was developed by NILFS development team.

       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)

nilfs-utils version 2.2		   Apr 2014			      NILFS(8)

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