Amdd

amdd is a tool that can be used to perform low-level I/O on using Amanda storage drivers. It is deprecated; new device types will not support the amdd interface, because it makes device assumptions that are not necessarily valid. For manual restore of devices, including new device types, use amrestore.

Name

amdd — Amanda version of dd

Synopsis

amdd [-d] [-l length] [if=input] [of=output] [bs=blocksize] [skip=count] [count=count]

DESCRIPTION

Amdd provides just enough of the standard UNIX dd command for the needs of Amanda. This is handy when doing a full restore and the standard dd program has not yet been found.

Amdd also provides access to the Amanda output drivers that support various tape simulations. This may be used for debugging or to convert from one format to another.

See the amanda(8) man page for more details about Amanda. See the OUTPUT DRIVERS section of amanda(8) for more information on the Amanda output drivers.

OPTIONS

-d

Turn on debugging output.

-llength

Set the output length. If the output driver limits the output size, this controls when end of tape will be simulated.

Length may have a multiplier suffix:

k = 1024 (Kilobytes)

b = 512 (Blocks)

M = 1024*1024 (Megabytes)

The default is no multiplier (bytes).

if=input

Input to dd. Default is stdin.

of=output

Where to send the output of dd. Default is stdout.

bs=blocksize

Size of each record. Input records smaller than this will not be padded. Output records will be the same size as the corresponding input record. Default is 512 bytes.

Blocksize may have a multiplier suffix:

k = 1024 (Kilobytes)

b = 512 (Blocks)

M = 1024*1024 (Megabytes)

The default is no multiplier (bytes).

count=count

Number of records to copy. Default is all records until end of file.

skip=count

Number of records to skip before copying input to output. Default is zero.

EXAMPLES

The first block (size 32k) of each image on a tape written by amanda contains the info about that image. A table of contents of an amanda backup tape:

TAPEDEV=/dev/nst0
ammt -t $TAPEDEV rewind
while ammt -t $TAPEDEV fsf 1
do
    amdd if=$TAPEDEV bs=32k count=1 | head -1
done

The same block contains also the command line you need to restore:

ammt -t $TAPEDEV rewind;  ammt -t $TAPEDEV fsf 12
amdd if=$TAPEDEV bs=32k count=1 | tr -d '\0\f'

The dumpimage is after that 32k header. Extract it and pipe it to e.g. gnutar:

ammt -t $TAPEDEV rewind;  ammt -t $TAPEDEV fsf 12
amdd if=$TAPEDEV bs=32k skip=1 | gtar -ztvf -

Using a diskfile (vtape) instead:

TAPEDEV=file:/amanda-vtapes/daily/slots
amdd if=$TAPEDEV bs=32k count=1

Hitting EOT of a virtual tape:

$ mkdir -p /space/vtapetst/data    # a "virtual" tape is a directory containing a subdir "data"
$ amdd -l 100k bs=32k if=/boot/vmlinuz of=file:/space/vtapetst
amdd: write error: No space left on device
5+0 in
3+1 out

AUTHOR

Marc Mengel <[email protected]>, John R. Jackson <[email protected]> : Original text

Stefan G. Weichinger, <[email protected]>, maintainer of the AMANDA-documentation: XML-conversion

SEE ALSO

amanda(8)