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How to Read EROS DATA CENTER Tapes Using DD

You will first need to know the structure of the tape. You will need to utilize two different methods. First, get the header info off of the tape. This can be done with the following command (on Eos):

	cat /dev/rmt/tps1d4nrnsv.8200 > header.out

This file contains the following two (3) lines:

PIXELS_PER_LINE=6879;
LINES_PER_DATA_FILE=6391;
NUMBER_OF_DATA_FILES=7;

When using 'dd', the first line is the blocksize and the second line is the count value. The third line is the number of files that you will be reading off of the tape (including the header)

Now, you must run imagine to find out how the data is laid out on the tape.

  1. start imagine
  2. select 'Import' off of the toolbar.
  3. Type is 'Generic Binary'
  4. Media is 'Tape'.
  5. Select the tape drive and press 'Data View...'
  6. This will bring up a window and it will automatically scan the first logical tape. When it is done, select 'auto scan' and wait for years.
  7. It will then give you a list that looks like this:
    	File 001,   Record 00001,     02540 bytes
    	File 002,   Record 17308,     02540 bytes
    	File 002,   Record 17309,     01369 bytes
    	File 003,   Record 32113,     01369 bytes
    	File 003,   Record 32114,     00992 bytes
    	File 004,   Record 44318,     00992 bytes
    	File 004,   Record 44319,     00233 bytes
    	File 005,   Record 188685,     00233 bytes
    	File 005,   Record 188686,     00084 bytes
    	File 006,   Record 523377,     00084 bytes
    	File 006,   Record 523378,     00021 bytes
    	File 007,   Record 2093509,     00021 bytes
    	File 008,   Record 2093509,     00021 bytes
    	File 009,   Record 00992,     00021 bytes
    	File 009,   Record 00993,     00011 bytes
    	File 010,   Record 06718,     00011 bytes
    	File 010,   Record 06719,     00005 bytes
    

    File 001 is the header we read off earlier. You will notice that some files are listed twice. For those files, we don't want the first instance, it is just a descriptor file. We want the second instance. So, using the 'fsf' option to 'mt' we can skip over it.

    Notice that the data view shows 10 files and the header said 7. There really aren't 10 files. Believe the header info over data view info.

As an example, I have included the whole 'dd' session that extracted the data using the above information:

=:eos-f:= cat /dev/rmt/tps1d4nrnsv.8200 > header.out
=:eos-f:= mt -t /dev/rmt/tps1d4nrnsv.8200 fsf 1
=:eos-f:= dd if=/dev/rmt/tps1d4nrnsv.8200 of=tape.02 bs=6879 count=6391
6391+0 records in
6391+0 records out
=:eos-f:= mt -t /dev/rmt/tps1d4nrnsv.8200 fsf 1
=:eos-f:= dd if=/dev/rmt/tps1d4nrnsv.8200 of=tape.03 bs=6879 count=6391
6391+0 records in
6391+0 records out
=:eos-f:= mt -t /dev/rmt/tps1d4nrnsv.8200 fsf 1
=:eos-f:= dd if=/dev/rmt/tps1d4nrnsv.8200 of=tape.04 bs=6879 count=6391
6391+0 records in
6391+0 records out
=:eos-f:= mt -t /dev/rmt/tps1d4nrnsv.8200 fsf 1
=:eos-f:= dd if=/dev/rmt/tps1d4nrnsv.8200 of=tape.05 bs=6879 count=6391
6391+0 records in
6391+0 records out
=:eos-f:= mt -t /dev/rmt/tps1d4nrnsv.8200 fsf 1
=:eos-f:= dd if=/dev/rmt/tps1d4nrnsv.8200 of=tape.06 bs=6879 count=6391
6391+0 records in
6391+0 records out
=:eos-f:= dd if=/dev/rmt/tps1d4nrnsv.8200 of=tape.07 bs=6879 count=6391
6391+0 records in
6391+0 records out

 

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