[geeks] Reading Sun DAT72 tapes... maybe...

[JP Hindin]

Good afternoon all;

A coworker sent me a pile of DAT72s (4mm DATs, 36GB/72GB compressed) that 
are all labeled:

StorageTek DAT72-170M
Media Recognition System

And have a Sun logo on them.

He's _pretty sure_ they should have software on them, but it is *possible* 
they were erased at some point. I have a "Dell" (Quantum) DAT72 drive that 
I picked up after discovering that the eight DAT drives I have in six 
different machines and on the shelf are all DDS1 through DDS4, naturally. 
The DAT72 drive reads and writes a tape I got with it (an HP branded tape, 
new in shrinkwrap), so it appears to be functional, however I am 
_completely_ unable to read anything off these Sun DAT72s. I'm using a 
Linux box with an Adaptec SCSI card at present.

Now, I will readily admit it's been a long time since I've used a tape 
drive, and even then I didn't have to be particularly creative about it. 
My belief is that I should be able to get _some_ kind of bytestream using 
dd, however all I get are I/O device errors.

I attempted to set the blksize to 0 (variable block size) which should 
have given me a leg-up on determining the correct block size that the tape 
was written with to get a valid stream if it was packed with something 
like tar, but again, I/O device errors.

If the tapes were erased my brain says I should at least see a leader 
block through dd, but perhaps not.

Does anyone know if there's something special about StorageTek "Media 
Recognition System" tapes that might explain why I can't get a viable 
bytestream from them?

I suspect my own incompetence is my obstacle here, so other wisdom is 
appreciated :)

My thanks;

  - JP