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From: igraham@SMAUG.PHYSICS.MCGILL.CA (Ian Graham)
Newsgroups: comp.sys.sgi
Subject: Re: exabyte tape weirdness
Message-ID: <9103010330.AA26687@smaug.physics.mcgill.ca>
Date: 1 Mar 91 03:30:02 GMT
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Jim Patterson <photon!sand!jhp%oasis3@ucsd.edu> writes....

>  [paraphrasing here, as I deleted his letter] I have noticed the bytes on
>  Iris Exabyte tapes are reversed compared with Suns.  Is this normal,
>  and is there a switch somewere to fix/modify it?

As far as I know that's just the way it is with Irises - I don't know
of any special switch to change it.  For some reason (I don't know why - does
anyone else?) they chose long ago to have a byte ordering the reverse 
of Sun, Dec, Apollo/HP etc.  This is true on all tape devices - QIC-150, 
reel-reel, etc, not just Exabyte.  Maybe even optical disks????

However, you can easily flip the bytes using dd, so that if you are reading 
a tape written on Sun machine (e.g. a tar format tape) you can extract 
it by using dd to reverse the bytes and piping this into tar:

         dd conv=swab if=/dev/device_name | tar -xvof -

It might run faster by specifying a bigger blocksize for dd - bs=5120, say -
I can't remember offhand.  Something similar can be cobbled up for bru or 
cpio.  As you can see, you are not the first to have encountered this!

Happy tape-reading/writing.

Ian  

    ___________________________________________ Ian Graham ______________
						igraham@physics.mcgill.ca
					        (514) 398-6526