Methods of reading a DDS Tape

[Kong Kian Chay]

I hav always been approached by users to help to read & retrieve files stored on Cartridge Tape by ex-staff years ago. The only info I get is that it is backup via a Unix system e.g. SCO-Unix, Solaris and IBM AIX. The users do NOT know what is the command used.

So far, I hav NEVER been successful in reading any of the tapes. Commands I used include :-
a) tar -tvf /dev/rmt/0m
b) dd if=/dev/rmt/0m bs=1k
c) cpio -it < /dev/rmt/0m ("-c" option tried as well)

May I know what other commands I can try (on HP-UX 10.20) to retrieve files from other variants of Unix. Any appropriate corrections to the above commands would also be appreciated.

NOTE : I will not be able to feedback on whether suggestions are able to retrieve files fr those tapes -- I do not hav the tapes -- but will definitely make use of the suggestions on the next enquiry from users.

[Juan González]

Hi,
I think that if dd isn't able to read from the tape it means that the tape was recorded in a drive using a format that your current drive doesn't support.

Best regards
JGM

[Ruediger Noack]

Hi,

the first step is to find an old box with old DDS drive that is able to physical read the first block of your tape with dd.
Than you find out the logical format of this reco file (tar, cpio, ...) with command file.
Use this logical command with different block size to read the complete tape.

Good Luck
Ruediger

[Carlos Fernandez Riera · Accepted solution]

1- if you run dd if=/dev/rmt/0mn of=/tmp/tape.1 bs=10k count=10

what is the message?
Is tape.1 0 bytes size?
No? run file /tmp/tape.1


2- Older driver writes in 512 bytes as physical block sizes. I think thah actual drivers can read old tapes, but if you need to try you can create a new special file for that tapes:


mksf -C tape -b DDS1 -H 4/0.0.0 -s 512
mksf -C tape -b DDS1 -H 4/0.0.0A -s 512 -n

Now you will found :
/dev/rmt/c?t?d?s512DDS1
/dev/rmt/c?t?d?s512DDS1n

Try with these ones.

[Joseph A Benaiah_1]

Kong,

You could try this:

dd if=/dev/rmt/0m of=/tmp/header count=10

file /tmp/header - which will give you the file format of the DDS tape.

Cheers,

Joseph.

[Kong Kian Chay]

Thanks everybody. I really appreciate all the responses received. Glad to have learnt more new things on HP-UX.

[Satish Y]

Hi,

you can use:

/usr/sbin/frecover -f /dev/rmt/0m -N -v

-N option Prevents frecover from actually recovering any files onto disk, but read the backup as if it was.

You can use frecover as it can read archives produced by fbackup as well as tar. You can go through man page of frecover for more informatin.

Regards,
Satish.

[Satish Y]

Sorry, bit confusion, cmd is:

/usr/sbin/frecover -N -v -f /dev/rmt/0m

Cheers...
Satish.