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* ChangeLog.1, ChangeLog.CVS, Makefile.am, NEWS, README: * README-hacking, directory, doc/Makefile.am, doc/dumpdir.texi: * doc/gendocs_template, doc/intern.texi, doc/mastermenu.el: * doc/snapshot.texi, doc/sparse.texi, doc/tar-snapshot-edit.texi: * doc/value.texi, lib/Makefile.am, scripts/backup-specs: * scripts/dump-remind.in, scripts/tar-snapshot-edit, scripts/tarcat: * scripts/xsparse.c, src/arith.h, src/buffer.c, src/compare.c: * src/create.c, src/delete.c, src/exit.c, src/suffix.c, src/tar.c: * src/tar.h, src/update.c, src/warning.c, src/xheader.c: * tests/append01.at, tests/append02.at, tests/atlocal.in: * tests/delete03.at, tests/exclude.at, tests/exclude06.at: * tests/extrac04.at, tests/extrac05.at, tests/extrac06.at: * tests/extrac07.at, tests/filerem01.at, tests/filerem02.at: * tests/incr01.at, tests/incr02.at, tests/incr03.at, tests/incr06.at: * tests/label02.at, tests/label03.at, tests/label04.at: * tests/label05.at, tests/link02.at, tests/link03.at: * tests/listed01.at, tests/listed02.at, tests/long01.at: * tests/longv7.at, tests/multiv01.at, tests/multiv02.at: * tests/multiv03.at, tests/multiv05.at, tests/multiv06.at: * tests/multiv07.at, tests/multiv08.at, tests/options.at: * tests/options02.at, tests/remfiles03.at, tests/rename01.at: * tests/rename02.at, tests/rename03.at, tests/rename04.at: * tests/rename05.at, tests/same-order01.at, tests/same-order02.at: * tests/shortfile.at, tests/shortupd.at, tests/sparse01.at: * tests/sparse02.at, tests/sparsemv.at, tests/sparsemvp.at: * tests/star/README, tests/star/gtarfail2.at: * tests/star/multi-fail.at: * tests/star/pax-big-10g.at, tests/star/quicktest.sh: * tests/star/ustar-big-2g.at, tests/star/ustar-big-8g.at: * tests/update01.at, tests/update02.at, tests/volsize.at: * tests/volume.at: Remove trailing spaces and tabs from lines, and remove trailing empty lines from files. This makes it a bit easier to share code among coreutils and other projects that do this.
58 lines
2.5 KiB
Plaintext
58 lines
2.5 KiB
Plaintext
@c This is part of the paxutils manual.
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@c Copyright (C) 2007 Free Software Foundation, Inc.
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@c This file is distributed under GFDL 1.1 or any later version
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@c published by the Free Software Foundation.
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@cindex Device numbers, changing
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@cindex snapshot files, editing
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@cindex snapshot files, fixing device numbers
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Sometimes device numbers can change after upgrading your kernel
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version or reconfiguring the hardware. Reportedly this is the case with
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some newer @i{Linux} kernels, when using @acronym{LVM}. In majority of
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cases this change is unnoticed by the users. However, it influences
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@command{tar} incremental backups: the device number is stored in tar
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snapshot files (@pxref{Snapshot Files}) and is used to determine whether
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the file has changed since the last backup. If the device numbers
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change for some reason, the next backup you run will be a full backup.
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@pindex tar-snapshot-edit
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To minimize the impact in these cases, GNU @command{tar} comes with
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the @command{tar-snapshot-edit} utility for inspecting and updating
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device numbers in snapshot files. The utility, written by
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Dustin J.@: Mitchell, is available from
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@uref{http://www.gnu.org/@/software/@/tar/@/utils/@/tar-snapshot-edit.html,
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@GNUTAR{} home page}.
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To obtain the device numbers used in the snapshot file, run
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@smallexample
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$ @kbd{tar-snapshot-edit @var{snapfile}}
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@end smallexample
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@noindent
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where @var{snapfile} is the name of the snapshot file (you can supply as many
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files as you wish in a single command line).
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To update all occurrences of the given device number in the file, use
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@option{-r} option. It takes a single argument of the form
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@samp{@var{olddev}-@var{newdev}}, where @var{olddev} is the device number
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used in the snapshot file, and @var{newdev} is the corresponding new device
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number. Both numbers may be specified in hex (e.g., @samp{0xfe01}),
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decimal (e.g., @samp{65025}), or as a major:minor number pair (e.g.,
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@samp{254:1}). To change several device numbers at once, specify them
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in a single comma-separated list, as in
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@option{-r 0x3060-0x4500,0x307-0x4600}.
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Before updating the snapshot file, it is a good idea to create a backup
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copy of it. This is accomplished by @samp{-b} option. The name of the
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backup file is obtained by appending @samp{~} to the original file name.
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An example session:
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@smallexample
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$ @kbd{tar-snapshot-edit /var/backup/snap.a}
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file version 2
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/tmp/snap: Device 0x0306 occurs 634 times.
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$ @kbd{tar-snapshot-edit -b -r 0x0306-0x4500 /var/backup/snap.a}
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file version 2
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@end smallexample
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