SUMMARY: Bootable Exabyte tape from SunOS cartridge tape

From: Allen Sonafrank (
Date: Thu Jan 16 1992 - 17:40:43 CST

My original query:

> Does anyone have experience making or using a SunOS 4.1.1 installation
> tape on an 8mm Exabyte cassette?
> My thought is to make such a tape from SunOS 4.1.1 150MB cartridge tapes,
> as a backup for a reseach project which will be taking Sparcstations to
> sea with only Exabyte tape drives (no cartridge tape drives on board).
> I imagine that it would be possible to dd the tape files one by one,
> and that it would be necessary to maintain the block sizes. I think
> block sizes only differ in the first five files.
> Does anyone know the details, or have a script or program which will
> copy the tapes?
> Has anyone tried this successfully, ie booted and installed SunOS from
> an Exabyte cassette tape?

I didn't get back a single response saying "Yes, I've done it, it
works", and several of the responses indicated that it wouldn't work
for various reasons (see below). People suggested using tcopy,
copytape, and tputil rather than dd to do the experiment.

Many people advised taking along one of Sun's supported boot devices.

The folks preparing for this particular cruise decided not
to try making an Exabyte boot tape, and will get by with two diskful
Sparcstations, each of which could be a boot server in a pinch.

Here are some of the comments I received:

I don't think it will ever work. Exabyte can write *only* 64512 byte
long blocks. Try to read a tape with dd and play with the block size
and you'll see what I mean....
I have copied the Sun installation tapes by dd'ing each tape file.
I use a blocksize of 50k and have had no trouble booting from them.
I haven't tried this with an Exabyte, though. You will probably
still have to use two tapes, unless you change the install scripts.
As far as I know, it isn't possible to boot from an Exabyte. Sure, you
could probably create a tape with a boot program and all the other boot
tape files on it, but that wouldn't be enough. The PROM monitor needs
to be able to talk at a pretty low level to the tape drive, and Exabytes
don't seem to like that. Besides, the boot file on the tape would need
to be modified for the specifics of the Exabyte.
there exists a PD program 'copytape' which should copy over the files
with the right block sizes. I tried this quite extensively - but had to
conclude, that it was (at least for me) not possible to boot a Sun from
an Exabyte tape.
I can't say I've ever tried it, but there is a program called copytape
at in the sun-source directory.
Solbourne optionally distributes its OS on 8mm; there are differences
between Solbournes and Suns, but the boot stuff seems to be close
enough. It should work, since the Exabyte looks like a generic
SCSI device. In the worst case you might have to dd the files onto
the 8mm tape with bs=512 and conv=sync to get around the boot loader
expecting an integer number of 512 byte blocks from a SCSI tape.

Your worst problem will probably be getting a copy of the boot program
for your tape, since SunOS is now on CD-ROMS.
You might try tcopy or tputil - tputil was created to do exactly what
you want.
The biggest problem with booting from Exabyte tapes is SCSI timeout.
The boot process does a lot of SHORT reads. The streaming tape, of course,
overshoots and has to be repositioned. Enough of this, and the reads from the
boot program time out waiting for the tape to become ready.

Many thanks to the following people who responded: (Leonardo C. Topa) (Mike Halderman) (Joe Garbarino)
kalli!kevin@fourx.Aus.Sun.COM (Kevin Sheehan {Consulting Poster Child})
millidc!indigo!djm@uunet.UU.NET (Drew Montag)
Mike Raffety <>
Rudolf Baumann <> (John M. Crowell)
George A. Planansky <> (Robert D Webber)
"Grootwassink, David" <>

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