Help with 1/2 inch Magnetic Tapes

[Jeremy Higdon]

In article <3495 at dftsrv.gsfc.nasa.gov>, buck at drax.gsfc.nasa.gov (Loren (Buck) Buchanan) writes:
> Hi SGI Fans,
> 
> Well, we got our 9-track drive, it is a Pertec FS2001-2.  I modified
> /dev/MAKEDEV by changing "KENNEDY*96X2" to "PERTEC*FS2001-2" to create 
> the various device files.  We can write and read back tapes, but we
> are unable to read tapes created on a foriegn machine (dd and our own
> custom software), by getting the cryptic anything error message
> 
>    "I/O error"
> 
> The tapes we write can be read on a Sun with a Cipher tape drive (via 
> dd or tar).
> 
> The foriegn tapes have variable length records up to 3970 bytes, I 
> would like to be able to read them directly with my own custome software,
> but a solution using dd would be appreciated.
> 
> The hardware specifics are:
>   SGI PI 4D/20 (low serial number, but more recent electronics module)
>   Pertec FS2001-2 (has a Pertec to SCSI board).
> 
> A quick side question, is how do I write variable length records on a
> 9-track tape?

Are you using the variable device?  If you are not, then using it may
answer both of your questions, as you can not generally read variable
blocksize tapes using the fixed block device.

"man tps" for more info.