[Info-vax] Exabyte tapes to disk

[Richard B. Gilbert]

Chris wrote:
> We have 8mm exabyte tapes with archived data on them. Our old vax
> machines could read/write these tapes with no problem with exabyte
> tape drives (SCSI connection). We would like to get the data off of
> these tapes and eventually onto disks (so that the data is more easily
> accessible, don't have to mess with tape drives etc.). However,
> whenever we use our vax to copy the data to disk, the files are not
> readable by other machines (e.g. there is a bunch of garbage before
> the data). We have been unable to find a way to use any other machine
> to copy the data from the tape to disk. Has anyone had any success
> with something like this? What worked?
> 
> Thanks for all your help,
> Chris

VMS is a "record oriented" system.  Contrast with Unix which denies the 
concept of records!  You can use records under Unix but you get no help 
from the O/S.  The O/S will hand you a wad of bytes and it's up to you 
to figure out where the record boundaries are.  Both approaches can be 
made to work.  As an old f... who grew up with 80 column punched cards
I tend to think in a record paradigm!

VMS can use fixed length records or variable length records.  Variable 
length records, IIRC, have a record length (16 bits) followed by the 
data.  A guess based on very skimpy evidence is that you have variable 
length records.

Indexed Sequential files have a somewhat more complex structure.

You can use the CONVERT utility on VMS to convert one record format to 
another.

If you happen to be in the Philadelphia (PA) area I would be delighted 
the help you figure it out; for a suitable fee, of course!  And with the 
understanding the the Exabyte tapes and drives are YOUR problem!  If you 
get the idea that I have had unsatisfactory experiences with 8mm tapes 
and drives, you are absolutely right!