amrestore.8

开源备份软件源码 AMANDA, the Advanced Maryland Automatic Network Disk Archiver, is a backup system that a

.\"     Title: amrestore
.\"    Author: 
.\" Generator: DocBook XSL Stylesheets v1.73.2 <http://docbook.sf.net/>
.\"      Date: 05/13/2008
.\"    Manual: 
.\"    Source: 
.\"
.TH "AMRESTORE" "8" "05/13/2008" "" ""
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.SH "NAME"
amrestore - extract backup images from an Amanda tape
.SH "SYNOPSIS"
.HP 10
\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
.RS 4
.nf
% amrestore \-p /dev/nrmt9 seine rz3g | restore \-ivbf 2 \-
.fi
.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
.RS 4
.nf
% amrestore /dev/nrmt9 seine
.fi
.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
.RS 4
.nf
seine\.rz1a\.19910125\.0
seine\.rz1g\.19910125\.0
.fi
.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
.RS 4
.nf
% amrestore \-p /amanda/20001119/seine\.rz1a\.2 | restore \-ivbf 2 \-
.fi
.RE
.PP
\fBAmrestore\fR
may be used to generate a listing of images on a tape:
.sp
.RS 4
.nf
% mt \-f /dev/nrmt9 rewind
% amrestore \-p /dev/nrmt9 no\-such\-host > /dev/null
.fi
.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 "AUTHOR"
.PP
James da Silva,
<jds@amanda\.org>, University of Maryland, College Park: Original text
.PP
Stefan G\. Weichinger,
<sgw@amanda\.org>, maintainer of the
\fIAmanda\fR\-documentation: XML\-conversion
.SH "SEE ALSO"
.PP
\fBamanda\fR(8),
\fBamdump\fR(8),
\fBamflush\fR(8),
\fBtar\fR(1),
\fBrestore\fR(8),
\fI\%http://wiki.zmanda.com\fR