141 lines
4.8 KiB
Groff
141 lines
4.8 KiB
Groff
.\" $NetBSD: lfs_cleanerd.8,v 1.18 2009/08/06 21:18:54 wiz Exp $
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.\"
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.\" Copyright (c) 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" from: @(#)lfs_cleanerd.8 8.2 (Berkeley) 12/11/93
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.\"
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.Dd August 6, 2009
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.Dt LFS_CLEANERD 8
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.Os
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.Sh NAME
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.Nm lfs_cleanerd
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.Nd garbage collect a log-structured file system
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.Sh SYNOPSIS
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.Nm
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.Op Fl bcDdfmqs
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.Op Fl i Ar segment-number
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.Op Fl l Ar load-threshhold
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.Op Fl n Ar number-of-segments
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.Op Fl r Ar report-frequency
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.Op Fl t Ar timeout
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.Pa node
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.Sh DESCRIPTION
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The
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.Nm
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command starts a daemon process which garbage-collects
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the log-structured file system residing at the point named by
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.Ar node
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in the global file system namespace.
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This command is normally executed by
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.Xr mount_lfs 8
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when the log-structured file system is mounted.
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The daemon will exit within a few minutes
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of when the file system it was cleaning is unmounted.
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.Pp
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Garbage collection on a log-structured file system is done by scanning
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the file system's segments for active, i.e. referenced, data and copying
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it to new segments.
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When all of the active data in a given segment has been copied to a new
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segment that segment can be marked as empty, thus reclaiming the space
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taken by the inactive data which was in it.
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.Pp
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The following options are available:
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.Bl -tag -width indent
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.It Fl b
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Use bytes written, rather than segments read, when determining how many
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segments to clean at once.
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.It Fl c
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Coalescing mode.
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For each live inode, check to see if it has too many
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blocks that are not contiguous, and if it does, rewrite it.
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After a single pass through the filesystem the cleaner will exit.
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This option has been reported to corrupt file data; do not use it.
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.It Fl D
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Stay in the foreground, do not become a daemon process.
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Does not print additional debugging information (in contrast to
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.Fl d ) .
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.It Fl d
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Run in debug mode.
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Do not become a daemon process, and print debugging information.
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More
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.Fl d
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s give more detailed debugging information.
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.It Fl f
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Use filesystem idle time as the criterion for aggressive cleaning,
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instead of system load.
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.It Fl i Ar segment-number
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Invalidate the segment with segment number
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.Ar segment-number .
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This option is used by
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.Xr resize_lfs 8 ,
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and should not be specified on the command line.
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.It Fl l Ar load-threshhold
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Clean more aggressively when the system load is below the given threshhold.
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The default threshhold is 0.2.
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.It Fl m
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Does nothing.
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This option is present for historical compatibility.
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.It Fl n Ar number-of-segments
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Clean this number of segments at a time: that is, pass this many
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segments' blocks through a single call to lfs_markv, or, if
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.Fl b
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was also given, pass this many segments' worth of blocks through a
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single call to lfs_markv.
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.It Fl q
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Quit after cleaning once.
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.It Fl r Ar report-frequency
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Give an efficiency report after every
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.Ar report-frequency
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times through the main loop.
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.It Fl s
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When cleaning the file system,
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send only a few blocks through lfs_markv at a time.
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Don't use this option.
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.It Fl t Ar timeout
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Poll the filesystem every
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.Ar timeout
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seconds, looking for opportunities to clean.
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The default is 300, that is, five minutes.
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Note that
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.Nm
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will be automatically awakened when the filesystem is active,
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so it is not usually necessary to set
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.Ar timeout
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to a low value.
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.El
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.Sh SEE ALSO
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.Xr lfs_bmapv 2 ,
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.Xr lfs_markv 2 ,
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.Xr lfs_segwait 2 ,
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.Xr mount_lfs 8
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.Sh HISTORY
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The
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.Nm
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utility first appeared in
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.Bx 4.4 .
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