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 expression descibe in the "HOST & DISK EXPRESSION" section
of
amanda(8).
Datestamp
are special expression describe 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.
Amrestore
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
amrestore
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
.Z
or
.gz
extension depending on whether
compress
or
gzip
is the preferred compression 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
.RAW
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 holding 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.
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:
