MV-II Diags Chapter 3

From: Gunther Schadow <>
Date: Tue Mar 19 01:41:39 2002

Doc Shipley wrote:

> WooHoo! Working copies of both the Maintenance & Customer
> diagnostic tapes!

that is good, nothing like achieving one's very own accomplishment :-)

> So I've got the contents of the tape on disk, with 2/3 of the files
> having a blocksize of 80.

BTW, those are VMS/ANSI file header and end-of-file blocks.

> The TUHS maketape doesn't know anything but
> N*512 blocksizes, so that's out, and the tape has to have a TapeMark at
> each file, so I can't just cat 'em all into a single file. I tried
> setting blocksize to 0 (variable) and running a dd loop, but the drive
> pukes with an "Undefined error" fairly quickly. So I just made a script
> that uses mt to set the blocksize every time it changes, and dd each
> file to tape. All 172 files. I couldn't remember how to compare file
> sizes in a test statement, so no loops. Bah!.

Well, get your sed/awk book out from the den or RTFM. (Sed
is so cool, I never need Perl if I have sed, awk and a bourne
shell.) But everyone accoring to his taste.

Only I have to bark at that mt blocksize hack. That isn't
necessary. All you need is dd! Dd really is your friend with
the ability to set the input (ibs) and output (obs) block size
differently (or all the same, bs).

The obs determines the block size written to tape:

dd if=file.01 of=/dev/nrmt0 bs=80

it's as easy as that. In my case I had the uVAX-II netbooted and the
read off the network causes the tape to stop and then re-position
for every block. That can slow down tape-writing by a factor of
10 or more. The trick is then to set ibs to 1 MB and obs to whatever
blocksize you need on tape. That way your tape stops only every
1 MB and then can happyly stream 200 or more consecutive blocks
without having to re-position.

> It's the Kludge from Hell, but it works. Anybody with a Unix system &
> a TK<whatever> oughta be able to use it.
> The 2 tarballs are about 1.5MB each. Assuming you have a license to
> use it, I see no reason not to help replace your media. :^)

1.5 MB? Mine was 5.5 MB and I have 255 files. What are you missing?


Gunther Schadow, M.D., Ph.D.          
Medical Information Scientist      Regenstrief Institute for Health Care
Adjunct Assistant Professor        Indiana University School of Medicine
Received on Tue Mar 19 2002 - 01:41:39 GMT

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