dd from tape vs. dd from file

[kenbrownct]

SCO release 5.0.6j; hardware is HP.

I used dd to dump copy a file "{file}" from a tape to the hard drive.

The following commands, however produce different results.

dd if=/dev/rst0 of=/tmp/file skip=4152 bs=32x1k count=2

dd if={file} of=/tmp/file2 skip=4152 bs=32x1k count=2

The dd command to the tape drive only appears to be skipping about 3146 blocks instead of 4152.

Any ideas on what I can change to make the tape dd successful?

 

[pcunix]

I'm assuming that you set the tape block size appropriately.
tape -a 512 setblk /dev/xStp0


Any possibility that it reached end of tape?

Tape controllers are very adamant about that- if you put 50 bytes on a tape with tar, nothing is going to give you back more than that- the controller just will not move the tape beyond the point where it last closed it off.



Tony Lawrence
SCO Unix/Linux Resources

http://pcunix.com

tony@pcunix.com