AMRESTORE(8)AMRESTORE(8)NAMEamrestore - extract backup images from an Amanda tape
SYNOPSISamrestore [-r-c-C] [-b�blocksize] [-f�fileno] [-l�label] [-p] [-h]
tapedevice holdingfile [hostname�[diskname�[datestamp�[host‐
name�[diskname�[datestamp...]]]]]]
DESCRIPTION
Amrestore extracts backup images from the tape mounted on tapedevice or
from the holding disk file holdingfile that match hostname, diskname
and datestamp patterns given on the command line. The tape or holding
file must be in a format written by the amdump or amflush program.
If diskname is not specified, all backups on the tape for the previous
hostname are candidates. If datestamp is not specified, all backups on
the tape for the previous hostname and diskname are candidates. If no
hostname, diskname or datestamp are specified, every backup on the tape
is a candidate.
Hostname and diskname are special expressions described in the "HOST &
DISK EXPRESSION" section of amanda(8). Datestamp are special expres‐
sion described in the "DATESTAMP EXPRESSION" section of amanda(8). For
example, if diskname is "rz[23]a", it would match disks rz2a and rz3a.
Datestamp is useful if amflush writes multiple backup runs to a single
tape.
Unless -p is used, candidate backup images are extracted to files in
the current directory named:
hostname.diskname.datestamp.dumplevel
Amrestore doesn't use a changer, it restore from the tape already
loaded in the tapedevice.
OPTIONS-b Set the blocksize used to read the tape or holding file. All
holding files must be read with a blocksize of 32 KBytes. Amre‐
store should normally be able to determine the blocksize for
tapes on its own and not need this parameter.
The default is 32 KBytes.
-f Do a rewind followed by a fsf <fileno> before trying to restore
an image.
-l Check if we restoring from the tape with the right label
-p Pipe output. The first matching backup image is sent to standard
output, which is normally a pipe to restore or tar, then amre‐
store quits. It may be run again to continue selecting backups
to process. Make sure you specify the no-rewind tapedevice when
doing this.
Note: restore may report "short read" errors when reading from a pipe.
Most versions of restore support a blocking factor option to let you
set the read block size, and you should set it to 2. See the example
below.
-c Compress output using the fastest method the compression program
provides. Amrestore normally writes output files in a format
understood by restore or tar, even if the backups on the tape
are compressed. With the -c or -C option, amrestore writes all
files in compressed format, even if the backups on the tape are
not compressed. Output file names will have a or extension
depending on whether compress or gzip is the preferred compres‐
sion program. This option is useful when the current directory
disk is small.
-C Compress output using the best method the compression program
provides (may be very CPU intensive). See the notes above about
the -c option.
-r Raw output. Backup images are output exactly as they are on the
tape, including the amdump headers. Output file names will have
a extension. This option is only useful for debugging and other
strange circumstances.
-h Header output. The tape header block is output at the beginning
of each file. This is like -r except -c or -C may also be used
to compress the result. Amrecover uses the header to determine
the restore program to use.
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 hold‐
ing file.
EXAMPLES
The following does an interactive restore of disk rz3g from host seine,
to restore particular files. Note the use of the b option to restore,
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.
% amrestore-p /dev/nrmt9 seine rz3g | restore -ivbf 2 -
The next example extracts all backup images for host seine. This is the
usual way to extract all data for a host after a disk crash.
% amrestore /dev/nrmt9 seine
If the backup datestamp in the above example is 19910125 and seine has
level 0 backups of disks rz1a and rz1g on the tape, these files will be
created in the current directory:
seine.rz1a.19910125.0
seine.rz1g.19910125.0
You may also use amrestore to extract a backup image from a holding
disk file that has not yet been flushed to tape:
% amrestore-p /amanda/20001119/seine.rz1a.2 | restore -ivbf 2 -
Amrestore may be used to generate a listing of images on a tape:
% mt -f /dev/nrmt9 rewind
% amrestore-p /dev/nrmt9 no-such-host > /dev/null
This asks amrestore to find images for host no-such-host. It will not
find any entries that match, but along the way will report each image
it skips.
CAVEATS
GNU-tar must be used to restore files from backup images created with
the GNUTAR dumptype. Vendor tar programs sometimes fail to read GNU tar
images.
AUTHOR
James da Silva, <jds@amanda.org>, University of Maryland, College Park:
Original text
Stefan G. Weichinger, <sgw@amanda.org>, maintainer of the Amanda-docu‐
mentation: XML-conversion
SEE ALSOamanda(8), amdump(8), amflush(8), tar(1)restore(8)AMRESTORE(8)
