🚀 go-pugleaf

Hi all,

I have been hunting round for weeks to try and solve this, but have
had no luck, so at last I am appealing to the net...

We have a Sun SLC running 4.1.3_U1 here with an HP 35480A DDS tape
drive attached.

This drive happily backs up and restores data though /dev/rst{0,8,16,24}
and /dev/nrst{0,8,16,24}.

I have a WangDAT 1300 DAT drive at home. Any tapes written on the
WangDAT read fine on the HP, but tapes written on the HP fail to read
at home on the WangDAT. I believe this is because the HP is a DDS1-DC
drive, and the WangDAT is just a plain DDS1 drive.

Consulting the limited specs we have on this drive seems to confirm
this; the HP will always automatically read uncompressed (Non DC)
tapes regardless of what mode it is in, and the suggested setup for
use with Suns turns the DC mode on by default.

I *really* want to be able to write tapes here that I can then read at
home, but I can't figure out how to acheive this. We would approach
the company that we bought the HP from, but they have gone bust, and
HP refuse to help us as "support is only available through OEM
dealers".

I have however found some docs that state that I can turn the
compression on and off using the "Mode Sense" and "Mode Select" SCSI
commands.

So, the solutions that occur to me are:

1) Change the DIP switches on the drive to default to no compression;
no good. People rely on being able to write compressed data from that
drive.

2) Find a program that toggles the state of the drive.

So, does anyone reading this have such a program please? Or even does
anyone have information on how to send SCSI commands to a specific
device?

I would be very grateful for any help anyone can offer.

Thanks.

Robin

P.S. Whilst I will obviously try and read these groups to check for
replies, emailed answers would be extremely useful too. Thanks.