[debian/amanda] / man / amrestore.8

'\" t
.\"     Title: amrestore
.\"    Author: James da Silva <jds@amanda.org>
.\" Generator: DocBook XSL Stylesheets vsnapshot_8273 <http://docbook.sf.net/>
.\"      Date: 11/05/2009
.\"    Manual: System Administration Commands
.\"    Source: Amanda 2.6.1p2
.\"  Language: English
.\"
.TH "AMRESTORE" "8" "11/05/2009" "Amanda 2\&.6\&.1p2" "System Administration Commands"
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.nh
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.SH "NAME"
amrestore \- extract backup images from an \fIAmanda\fR tape
.SH "SYNOPSIS"
.HP \w'\fBamrestore\fR\ 'u
\fBamrestore\fR [\-r | \-c | \-C] [\-b | \fIblocksize\fR] [\-f | \fIfileno\fR] [\-l | \fIlabel\fR] [\-p] [\-h] \fItapedevice\fR|\ \fIholdingfile\fR  [\fIhostname\fR [\fIdiskname\fR [\fIdatestamp\fR [\fIhostname\fR [\fIdiskname\fR [\fIdatestamp\fR | \&.\&.\&.]]]]]]
.SH "DESCRIPTION"
.PP
\fBAmrestore\fR
extracts backup images from the tape mounted on
\fItapedevice\fR
or from the holding disk file
\fIholdingfile\fR
that match
\fIhostname\fR,
\fIdiskname\fR
and
\fIdatestamp\fR
patterns given on the command line\&. The tape or holding file must be in a format written by the
\fBamdump\fR
or
\fBamflush\fR
program\&.
.PP
If
\fIdiskname\fR
is not specified, all backups on the tape for the previous
\fIhostname\fR
are candidates\&. If
\fIdatestamp\fR
is not specified, all backups on the tape for the previous
\fIhostname\fR
and
\fIdiskname\fR
are candidates\&. If no
\fIhostname\fR,
\fIdiskname\fR
or
\fIdatestamp\fR
are specified, every backup on the tape is a candidate\&.
.PP
\fIHostname\fR
and
\fIdiskname\fR
are special expressions described in the "HOST & DISK EXPRESSION" section of
\fBamanda\fR(8)\&.
\fIDatestamp\fR
are special expression described in the "DATESTAMP EXPRESSION" section of
\fBamanda\fR(8)\&. For example, if
\fIdiskname\fR
is "rz[23]a", it would match disks
\fBrz2a\fR
and
\fBrz3a\fR\&.
.PP
\fIDatestamp\fR
is useful if
\fBamflush\fR
writes multiple backup runs to a single tape\&.
.PP
Unless
\fB\-p\fR
is used, candidate backup images are extracted to files in the current directory named:
.PP
\fIhostname\&.diskname\&.datestamp\&.dumplevel\fR
.PP
Amrestore doesn\'t use a changer, it restore from the tape already loaded in the
\fItapedevice\&.\fR
.SH "OPTIONS"
.PP
\fB\-b\fR
.RS 4
Set the blocksize used to read the tape or holding file\&. All holding files must be read with a blocksize of 32 KBytes\&.
\fBAmrestore\fR
should normally be able to determine the blocksize for tapes on its own and not need this parameter\&.
.RE
.PP
The default is 32 KBytes\&.
.PP
\fB\-f\fR
.RS 4
Do a rewind followed by a fsf <fileno> before trying to restore an image\&.
.RE
.PP
\fB\-l\fR
.RS 4
Check if we restoring from the tape with the right
\fIlabel\fR
.RE
.PP
\fB\-p\fR
.RS 4
Pipe output\&. The first matching backup image is sent to standard output, which is normally a pipe to
\fBrestore\fR
or
\fBtar\fR, then
\fBamrestore\fR
quits\&. It may be run again to continue selecting backups to process\&. Make sure you specify the no\-rewind
\fItapedevice\fR
when doing this\&.
.RE
.PP
Note:
\fBrestore\fR
may report "short read" errors when reading from a pipe\&. Most versions of
\fBrestore\fR
support a blocking factor option to let you set the read block size, and you should set it to 2\&. See the example below\&.
.PP
\fB\-c\fR
.RS 4
Compress output using the fastest method the compression program provides\&.
\fBAmrestore\fR
normally writes output files in a format understood by
\fBrestore\fR
or
\fBtar\fR, even if the backups on the tape are compressed\&. With the
\fB\-c\fR
or
\fB\-C\fR
option,
\fBamrestore\fR
writes all files in compressed format, even if the backups on the tape are not compressed\&. Output file names will have a
\fB\&.Z\fR
or
\fB\&.gz\fR
extension depending on whether
\fBcompress\fR
or
\fBgzip\fR
is the preferred compression program\&. This option is useful when the current directory disk is small\&.
.RE
.PP
\fB\-C\fR
.RS 4
Compress output using the best method the compression program provides (may be very CPU intensive)\&. See the notes above about the
\fB\-c\fR
option\&.
.RE
.PP
\fB\-r\fR
.RS 4
Raw output\&. Backup images are output exactly as they are on the tape, including the
\fBamdump\fR
headers\&. Output file names will have a
\fB\&.RAW\fR
extension\&. This option is only useful for debugging and other strange circumstances\&.
.RE
.PP
\fB\-h\fR
.RS 4
Header output\&. The tape header block is output at the beginning of each file\&. This is like
\fB\-r\fR
except
\fB\-c\fR
or
\fB\-C\fR
may also be used to compress the result\&.
\fBAmrecover\fR
uses the header to determine the restore program to use\&.
.RE
.PP
If a header is written (\-r or \-h), only 32 KBytes are output regardless of the tape blocksize\&. This makes the resulting image usable as a holding file\&.
.PP
\fB\-o\fR \fIconfigoption\fR
.RS 4
See the "\fBCONFIGURATION OVERRIDE\fR" section in
\fBamanda\fR(8)\&.
.RE
.SH "EXAMPLES"
.PP
The following does an interactive restore of disk
\fIrz3g\fR
from host
\fIseine\fR, to restore particular files\&. Note the use of the
\fBb\fR
option to
\fBrestore\fR, which causes it to read in units of two 512\-byte blocks (1 Kbyte) at a time\&. This helps keep it from complaining about short reads\&.
.sp
.if n \{\
.RS 4
.\}
.nf
% amrestore \-p /dev/nrmt9 seine rz3g | restore \-ivbf 2 \-
.fi
.if n \{\
.RE
.\}
.PP
The next example extracts all backup images for host
\fIseine\fR\&. This is the usual way to extract all data for a host after a disk crash\&.
.sp
.if n \{\
.RS 4
.\}
.nf
% amrestore /dev/nrmt9 seine
.fi
.if n \{\
.RE
.\}
.PP
If the backup datestamp in the above example is
19910125
and
\fIseine\fR
has level 0 backups of disks
\fIrz1a\fR
and
\fIrz1g\fR
on the tape, these files will be created in the current directory:
.sp
.if n \{\
.RS 4
.\}
.nf
seine\&.rz1a\&.19910125\&.0
seine\&.rz1g\&.19910125\&.0
.fi
.if n \{\
.RE
.\}
.PP
You may also use
\fBamrestore\fR
to extract a backup image from a holding disk file that has not yet been flushed to tape:
.sp
.if n \{\
.RS 4
.\}
.nf
% amrestore \-p /amanda/20001119/seine\&.rz1a\&.2 | restore \-ivbf 2 \-
.fi
.if n \{\
.RE
.\}
.PP
\fBAmrestore\fR
may be used to generate a listing of images on a tape:
.sp
.if n \{\
.RS 4
.\}
.nf
% mt \-f /dev/nrmt9 rewind
% amrestore \-p /dev/nrmt9 no\-such\-host > /dev/null
.fi
.if n \{\
.RE
.\}
.PP
This asks
\fBamrestore\fR
to find images for host
\fBno\-such\-host\fR\&. It will not find any entries that match, but along the way will report each image it skips\&.
.SH "CAVEATS"
.PP
\fBGNU\-tar\fR
must be used to restore files from backup images created with the GNUTAR dumptype\&. Vendor tar programs sometimes fail to read GNU tar images\&.
.SH "SEE ALSO"
.PP
\fBamanda\fR(8),
\fBamdump\fR(8),
\fBamflush\fR(8),
\fBtar\fR(1),
\fBrestore\fR(8),
: http://wiki.zmanda.com
.SH "AUTHORS"
.PP
\fBJames da Silva\fR <\&jds@amanda\&.org\&>
.PP
\fBStefan G\&. Weichinger\fR <\&sgw@amanda\&.org\&>