jhp%oasis3@sand.UUCP (Jim Patterson) (03/01/91)
I just installed an Exabyte tape on my PI (4D/25, 3.3.1). The tape came from a 3rd party vendor. It works just fine with all the SGI tape utilities (bru, tar, etc). I have noticed one very strange thing. When I read a tape generated on two different (non SGI) systems the data comes in byte swapped. Tapes that are written on the SGI also appear to be byte swapped on the other system. Does anybody have any idea what is going on? Is there some configuration switch I need to use to make the tapes compatible between the two systems ? -- Jim Patterson photon!jhp@ucsd.edu uunet!photon!jhp
igraham@SMAUG.PHYSICS.MCGILL.CA (Ian Graham) (03/01/91)
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
olson@anchor.esd.sgi.com (Dave Olson) (03/02/91)
In <9102282334.AA01973@sand> jhp%oasis3@sand.UUCP (Jim Patterson) writes: | I just installed an Exabyte tape on my PI (4D/25, 3.3.1). The tape | came from a 3rd party vendor. It works just fine with all the SGI tape | utilities (bru, tar, etc). | | I have noticed one very strange thing. When I read a tape generated | on two different (non SGI) systems the data comes in byte swapped. | Tapes that are written on the SGI also appear to be byte swapped on | the other system. | | Does anybody have any idea what is going on? Is there some | configuration switch I need to use to make the tapes compatible | between the two systems ? Try man tps MAKEDEV. One of the advantages of buying from us is that you get documentation. We make links to the byte swapping device by default (ONLY for QIC tapes) to be compatible with the older 68k machines which had a byte swapping controller. If you do: su; cd /dev; rm *tape*; ./MAKEDEV tps tapelinks then your /dev/tape will point to the non-byteswapped fixed block device. -- Dave Olson Life would be so much easier if we could just look at the source code.