64a16434d8
When using a kernel built with the GZIO config option, dumpon -z can be used to configure gzip compression using the in-kernel copy of zlib. This is useful on systems with large amounts of RAM, which require a correspondingly large dump device. Recovery of compressed dumps is also faster since fewer bytes need to be copied from the dump device. Because we have no way of knowing the final size of a compressed dump until it is written, the kernel will always attempt to dump when compression is configured, regardless of the dump device size. If the dump is aborted because we run out of space, an error is reported on the console. savecore(8) is modified to handle compressed dumps and save them to vmcore.<index>.gz, as it does when given the -z option. A new rc.conf variable, dumpon_flags, is added. Its value is added to the boot-time dumpon(8) invocation that occurs when a dump device is configured in rc.conf. Reviewed by: cem (earlier version) Discussed with: def, rgrimes Relnotes: yes Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D11723
190 lines
5.1 KiB
Groff
190 lines
5.1 KiB
Groff
.\" Copyright (c) 1980, 1991, 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: @(#)savecore.8 8.1 (Berkeley) 6/5/93
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.\" $FreeBSD$
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.\"
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.Dd October 24, 2017
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.Dt SAVECORE 8
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.Os
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.Sh NAME
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.Nm savecore
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.Nd "save a core dump of the operating system"
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.Sh SYNOPSIS
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.Nm
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.Fl c
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.Op Fl v
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.Op Ar device ...
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.Nm
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.Fl C
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.Op Fl v
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.Op Ar device ...
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.Nm
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.Op Fl -libxo
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.Op Fl fkvz
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.Op Fl m Ar maxdumps
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.Op Ar directory Op Ar device ...
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.Sh DESCRIPTION
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The
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.Nm
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utility
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copies a core dump into
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.Ar directory ,
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or the current working directory if no
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.Ar directory
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argument is given,
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and enters a reboot message and information about the core dump into
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the system log.
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.Pp
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The options are as follows:
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.Bl -tag -width ".Fl m Ar maxdumps"
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.It Fl -libxo
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Generate output via
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.Xr libxo 3
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in a selection of different human and machine readable formats.
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See
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.Xr xo_parse_args 3
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for details on command line arguments.
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.It Fl C
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Check to see if a dump exists,
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and display a brief message to indicate the status.
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An exit status of 0 indicates that a dump is there,
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1 indicates that none exists.
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This option is compatible only with the
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.Op Fl v
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option.
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.It Fl c
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Clear the dump, so that future invocations of
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.Nm
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will ignore it.
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.It Fl f
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Force a dump to be taken even if either the dump was cleared or if the
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dump header information is inconsistent.
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.It Fl k
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Do not clear the dump after saving it.
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.It Fl m Ar maxdumps
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Maximum number of dumps to store.
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Once the number of stored dumps is equal to
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.Ar maxdumps
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the counter will restart from
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.Dv 0 .
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.It Fl v
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Print out some additional debugging information.
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Specify twice for more information.
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.It Fl z
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Compress the dump (see
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.Xr gzip 1 ) .
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The dump may already be compressed if the kernel was configured to
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do so by
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.Xr dumpon 8 .
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In this case, the option has no effect.
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.El
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.Pp
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The
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.Nm
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utility
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looks for dumps on each device specified by the
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.Ar device
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argument(s), or on each device in
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.Pa /etc/fstab
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marked as
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.Dq dump
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or
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.Dq swap .
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The
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.Nm
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utility
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checks the core dump in various ways to make sure that it is complete.
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If it passes these checks, it saves the core image in
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.Ar directory Ns Pa /vmcore.#
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and information about the core in
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.Ar directory Ns Pa /info.# .
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If the core is encrypted, it saves the dump key in
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.Ar directory Ns Pa /key.# .
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The core can be later decrypted using
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.Xr decryptcore 8 .
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For kernel textdumps generated with the
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.Xr textdump 4
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facility, output will be stored in the
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.Xr tar 5
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format and named
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.Ar directory Ns Pa /textdump.tar.# .
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The
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.Dq #
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is the number from the first line of the file
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.Ar directory Ns Pa /bounds ,
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and it is incremented and stored back into the file each time
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.Nm
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successfully runs.
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.Pp
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The
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.Nm
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utility
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also checks the available disk space before attempting to make the copies.
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If there is insufficient disk space in the file system containing
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.Ar directory ,
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or if the file
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.Ar directory Ns Pa /minfree
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exists and the number of free kilobytes (for non-superusers) in the
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file system after the copies were made would be less than the number
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in the first line of this file, the copies are not attempted.
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.Pp
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If
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.Nm
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successfully copies the kernel and the core dump, the core dump is cleared
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so that future invocations of
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.Nm
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will ignore it.
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.Pp
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The
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.Nm
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utility
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is meant to be called near the end of the initialization file
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.Pa /etc/rc
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(see
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.Xr rc 8 ) .
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.Sh SEE ALSO
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.Xr gzip 1 ,
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.Xr getbootfile 3 ,
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.Xr libxo 3 ,
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.Xr xo_parse_args 3 ,
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.Xr textdump 4 ,
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.Xr tar 5 ,
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.Xr decryptcore 8 ,
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.Xr dumpon 8 ,
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.Xr syslogd 8
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.Sh HISTORY
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The
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.Nm
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utility appeared in
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.Bx 4.1 .
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.Pp
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Support for kernel textdumps appeared in
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.Fx 7.1 .
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.Sh BUGS
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The minfree code does not consider the effect of compression or sparse files.
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