4e3fced95b
Kernels and tools understand both v1 and v2 filesystems; newfs_lfs generates v2 by default. Changes for the v2 layout include: - Segments of non-PO2 size and arbitrary block offset, so these can be matched to convenient physical characteristics of the partition (e.g., stripe or track size and offset). - Address by fragment instead of by disk sector, paving the way for non-512-byte-sector devices. In theory fragments can be as large as you like, though in reality they must be smaller than MAXBSIZE in size. - Use serial number and filesystem identifier to ensure that roll-forward doesn't get old data and think it's new. Roll-forward is enabled for v2 filesystems, though not for v1 filesystems by default. - The inode free list is now a tailq, paving the way for undelete (undelete is not yet implemented, but can be without further non-backwards-compatible changes to disk structures). - Inode atime information is kept in the Ifile, instead of on the inode; that is, the inode is never written *just* because atime was changed. Because of this the inodes remain near the file data on the disk, rather than wandering all over as the disk is read repeatedly. This speeds up repeated reads by a small but noticeable amount. Other changes of note include: - The ifile written by newfs_lfs can now be of arbitrary length, it is no longer restricted to a single indirect block. - Fixed an old bug where ctime was changed every time a vnode was created. I need to look more closely to make sure that the times are only updated during write(2) and friends, not after-the-fact during a segment write, and certainly not by the cleaner.
125 lines
4.5 KiB
Groff
125 lines
4.5 KiB
Groff
.\" $NetBSD: lfs_cleanerd.8,v 1.9 2001/07/13 20:30:22 perseant 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. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. 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 December 11, 1993
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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 bdfmqs
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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 d
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Run in debug mode.
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Do not become a daemon process, and print debugging information. 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 l Ar load-threshhold
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Clean more aggressively when the system load is below the given
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threshhold. The default threshhold is 0.2.
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.It Fl m
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Use mmap, rather than rereading the Ifile to update the cleaner's
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knowledge of the filesystem. Do not use this option.
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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, send only a few blocks through lfs_markv
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at a time. 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. The default is 300, that
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is, five minutes. Note that
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.Nm
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will be automatically awakened when the filesystem is active, so it is
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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 mount_lfs 8
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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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.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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