🚀 go-pugleaf

In article <1992Aug11.123646.20532@ultb.isc.rit.edu>, ecldco@ultb.isc.rit.edu
(E.C. Loyd) writes:
>[lots of stuff relating to copying TA90s deleted]
>>A warning! It is important to note that when you copy tapes, 
>>error blocks may appear/disappear. If you are copying VMS BACKUP 
>>savesets, it is extremely important that you leave on the CRC 
>>checking and redundancy grouping capabilities of VMS BACKUP. 
>>Otherwise, there is a distinct chance that your saveset may get 
>>corrupted. 
>
>But what we here at RIT would like to do it copy, bit-for-bit, one tape to
>another tape.  There would be no loss of data in this fashion.

There is a backup qualifier called /INTERCHANGE that changes the
characteristiics of error block recovery on tape [I think a 'small' blocksize
such as 8192 might have to be specified as well - (?)].  Both /INTERCHANGE and
/BLOCK=8192 are specified on VMSINSTAL savesets for example, which allows you
to use the COPY command between disk/tape, disk/disk and tape/tape.

I think the answer is that if you have tapes that you want copied that don't
meet the above criteria, you are out of luck in terms of reliable data
transfer.  You might be able to play games with them to get partial recovery,
but I wouldn't want to depend on the results.
____________________________________________________________________________
Harvey Brydon         | Internet:   brydon@dsn.SINet.slb.com
Dowell Schlumberger   | P.O.T.S.:   (918)250-4312
  ...then there was the Aggie that won a gold medal and had it bronzed.