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The domain of NILFS project home was changed to nilfs.sourceforge.io to enable https access. This replaces ths URL strings "http://nilfs.sourceforge.net" in man pages with "https://nilfs.sourceforge.io". Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
125 lines
4.6 KiB
Groff
125 lines
4.6 KiB
Groff
.\" Copyright (C) 2005-2012 Nippon Telegraph and Telephone Corporation.
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.\" Written by Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
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.\"
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.TH NILFS 8 "Apr 2014" "nilfs-utils version 2.2"
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.SH NAME
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NILFS \- the new implementation of a log-structured file system
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.SH SYNOPSIS
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Overview of the NILFS file system and the related tools.
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.SH DESCRIPTION
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NILFS is a log-structured file system developed for Linux. NILFS
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provides versioning capability of an entire file system and continuous
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snapshotting that allows users to restore files mistakenly overwritten
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or destroyed a while ago.
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.PP
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The current major version of NILFS is version 2, which is referred to
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as NILFS2. NILFS2 is equipped with an online garbage collector (also
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called cleaner) that reclaims disk space in the background with
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keeping multiple snapshots.
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.PP
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When data is written or any change is made to a NILFS2 file system, it
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automatically creates a checkpoint. A checkpoint represents a
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consistent state of the NILFS2 file system of a certain instant. It
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becomes mountable after being changed into a snapshot. A snapshot is
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the checkpoint marked not to be deleted by the cleaner. NILFS2
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creates a number of checkpoints at regular intervals (unless there is
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no change) or with synchronous writings. There is no practical limit
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on the number of checkpoints and snapshots.
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.PP
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The following tools are available to manage the checkpoint and the
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snapshot:
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.TP 12
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\fBlscp\fP
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lists checkpoints or snapshots
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.TP
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\fBmkcp\fP
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makes a checkpoint or a snapshot
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.TP
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\fBchcp\fP
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changes an existing checkpoint to a snapshot or vice versa
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.TP
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\fBrmcp\fP
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invalidates specified checkpoint(s)
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.PP
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These tools give the versioning capability to NILFS2; a user can
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select significant versions among continuously created checkpoints and
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can change them to snapshots to be preserved for long periods.
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.PP
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Every checkpoint except for the snapshot will become unprotected from
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the cleaner after a given period of time. This period is controlled
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by the \fBprotection_period\fP parameter defined in the
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\fB/etc/nilfs_cleanerd.conf\fP(5) file.
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.SH MOUNT OPTIONS
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Refer to the
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.BR mount.nilfs2 (8).
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.SH EXAMPLES
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.TP
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.B mkfs \-t nilfs2 \fP/dev/sdb1
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creates a NILFS2 file system on a block device `/dev/sdb1'.
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.TP
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.B mount \-t nilfs2 \fP/dev/sdb1 /nilfs
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mounts the NILFS2 file system on a mount point `/nilfs' like an
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ordinary POSIX file system. This will invoke a cleaner process
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\fBnilfs_cleanerd\fP(8) through an external mount program
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(i.e. \fBmount.nilfs2\fP(8)).
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.TP
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.B lscp
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lists checkpoints created in the file system as follows:
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.PP
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CNO DATE TIME MODE FLG BLKCNT ICNT
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1 2014-01-18 20:49:54 cp - 4 2
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2 2014-01-18 20:51:45 cp - 3990 11
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3 2014-01-18 20:51:45 cp - 6058 3
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4 2014-01-18 20:51:49 cp - 4807 6
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5 2014-01-18 20:51:49 cp - 262 3
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...
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.TP
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.B chcp ss \fP2
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changes the checkpoint whose \fIcheckpoint-number\fP is two to a snapshot.
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Then the checkpoint list will become as follows:
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.PP
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CNO DATE TIME MODE FLG BLKCNT ICNT
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1 2014-01-18 20:49:54 cp - 4 2
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2 2014-01-18 20:51:45 ss - 3990 11
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3 2014-01-18 20:51:45 cp - 6058 3
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4 2014-01-18 20:51:49 cp - 4807 6
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5 2014-01-18 20:51:49 cp - 262 3
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...
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.TP
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.B mount \-t nilfs2 \-r \-o cp=2 \fP/dev/sdb1 /snapshot
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mounts the snapshot on another directory `/snapshot' as a read-only
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file system. Here the snapshot mount requires at least two options, a
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read-only option (\fB\-r\fP or \fB\-o ro\fP) and the \fBcp\fP option
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(\fB\-o cp=\fP\fIcheckpoint-number\fP). Note that a read/write mount and
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one or more snapshots are mountable independently, so the online
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backup is possible through the snapshot mounts.
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.PP
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# mount \-t nilfs2
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/dev/sdb1 on /nilfs type nilfs2 (rw,gcpid=13296)
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/dev/sdb1 on /snapshot type nilfs2 (ro,cp=2)
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.TP
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.B umount \fP/nilfs
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unmounts the NILFS2 file system mounted on `/nilfs' and will shutdown
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the \fBnilfs_cleanerd\fP(8) through an external umount program
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(\fBumount.nilfs2\fP(8)) for the read/write mount.
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.SH AUTHORS
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.B NILFS2
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was developed by NILFS development team.
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.SH SEE ALSO
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.BR mkfs.nilfs2 (8),
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.BR mount.nilfs2 (8),
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.BR umount.nilfs2 (8),
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.BR nilfs_cleanerd (8),
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.BR nilfs_cleanerd.conf (5),
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.BR nilfs-tune (8),
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.BR nilfs-clean (8),
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.BR nilfs-resize (8),
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.BR lscp (1),
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.BR mkcp (8),
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.BR chcp (8),
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.BR rmcp (8),
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.BR lssu (1),
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.BR dumpseg (8)
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.sp
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https://nilfs.sourceforge.io/
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