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91 lines
2.9 KiB
Groff
91 lines
2.9 KiB
Groff
.\"
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.\" Copyright (c) 2003 Networks Associates Technology, Inc.
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.\" All rights reserved.
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.\"
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.\" This software was developed for the FreeBSD Project by Marshall
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.\" Kirk McKusick and Network Associates Laboratories, the Security
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.\" Research Division of Network Associates, Inc. under DARPA/SPAWAR
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.\" contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA CHATS
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.\" research program.
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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. The names of the authors may not be used to endorse or promote
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.\" products derived from this software without specific prior written
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.\" permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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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.\" $FreeBSD$
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.\"
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.Dd February 14, 2011
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.Dt MKSNAP_FFS 8
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.Os
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.Sh NAME
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.Nm mksnap_ffs
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.Nd take a file system snapshot
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.Sh SYNOPSIS
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.Nm
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.Ar snapshot_name
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.Sh DESCRIPTION
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The
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.Nm
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utility creates a snapshot named
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.Ar snapshot_name .
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.Pp
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The group ownership of the file is set to
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.Dq Li operator ;
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the owner of the file remains
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.Dq Li root .
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The mode of the snapshot is set to be readable by the owner
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or members of the
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.Dq Li operator
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group.
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.Sh EXAMPLES
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Create a snapshot of
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.Pa /usr/home
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file system and mount the snapshot elsewhere:
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.Bd -literal -offset indent
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mksnap_ffs /usr/home/snapshot
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mdconfig -a -t vnode -o readonly -f /usr/home/snapshot
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mount -o ro /dev/md0 /mnt/
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.Ed
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.Sh SEE ALSO
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.Xr chmod 2 ,
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.Xr chown 8 ,
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.Xr mdconfig 8 ,
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.Xr mount 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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.Fx 5.0 .
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.Sh CAVEATS
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The disk full situation is not handled gracefully and may
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lead to a system panic when no free blocks are found.
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.Pp
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Every filesystem can have only up to 20 active snapshots.
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When this limit is reached, attempting to create more snapshots
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fails with
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.Er ENOSPC ,
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and
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.Nm
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reports that it is
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.Dq out of space .
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