SUMMARY: Reading a tape written in a DLT4000 in a DLT7000 drive

From: Brett Lymn (
Date: Tue Jul 25 2000 - 02:49:47 CDT

Last week I sent out this plea:

> I have been given an Overland tape robot to use on a Solaris
>2.5.1 E420R. I have the robot under control using stctl which works
>fine (for all those who have been asking recently :-)
>The problem I have is that the beast has two DLT7000 tape drives in
>it. I can talk to the tape drives ok, mt gives me a status back, I
>can dd our backup tape header off a tape written by a DLT4000 _but_
>when I try to perform a ufsrestore from a tape written by a DLT4000
>ufsrestore spits out a read error. The very same tape reads fine on a
>DLT4000 tape drive.
>Here are the parameter lines we are using in st.conf:
>DLT4000 = 1,0x36,0,0x8219,4,0x17,0x18,0x82,0x83,3;
>dlt7000-data = 1,0x36,0,0xD619,4,0x82,0x83,0x84,0x85,3;
>Note that, yes, I have tried all the l,h,c,u devices with the same
>result. The tapes were written on the DLT4000 with the /dev/rmt/0c
>tape device which if I have it right means it used mode 0x83 which
>should be the /dev/rmt/1m device when using the DLT7000, no?

Firstly, thanks to all the people who sent their tape config lines to
me to try. It looks like there is a lot of variations out there but
not in anything that makes a big difference (being a programmer and
understanding yacc grammar helps being able to read the st man page :-)

The short answer is that my parameter line for the DLT7000 was ok but
I had the tape config list entry incorrect (had Quantum instead of
QUANTUM) so I was picking up the Sun default entry which did not
work. I was confused because the label the Sun entry emits was
exactly like the one I used. It was only when I turned off variable
tape blocking and the st driver still used it that I woke up. So, I
can read the DLT4000 tapes fine with the above dtl7000-data.

Big thanks to:

Eric S. Bryant
Arthur Darren Dunham
Bernhard Sadlowski
Ken Robson

and one person who preferred not to be indentified

Brett Lymn, Computer Systems Administrator, BAE SYSTEMS

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