[HECnet] VMS 5.4 backup

[Johnny Billquist]

On 2016-05-29 10:50, Hans Vlems wrote:
> With tapes you'd better get the data off the media and to a disk.

I think that is what Peter is doing... :-)

> First off, clean the tape heads!

Always a good suggestion.

> - try a straight forward copy: this may fail for several reasons depending on what tape you have.
> - use backup to perform the copy
>  $ backup mua0:*.* ‎dua4:[savesets]/log
> Should that fail, try to mount the tape foreign and use copy. If VMS complains then SET RMS may be useful.

Not sure what the point was here. The actual reading from the tape runs 
through the save device driver in all three cases, so any tape error 
handling will be the same. However, backup might have additional 
recovery heuristics to deal with possible read errors. Copying the file 
to disk will most likely defeat any recovery ability in backup, so I 
don't really see much gain in doing that. If the tape can be read, all 
the methods work equally well. If the tape can't be read, copying will 
possibly loose more information than using backup, but in either case, 
and unrecoverable error that would prevent any further operation will 
act the same with all methods.

So, back to Peter's question - I don't know the answer. Is there a way 
to tell backup to stop at errors instead of continuing? (I guess I could 
fire up a VMS system, and read help pages, but I'm sure there are people 
here who already have this available and can check things up.)

	Johnny

> Good luck
>
> Verzonden vanaf mijn BlackBerry 10-smartphone.
>   Origineel bericht
> Van: Peter Lothberg
> Verzonden: zondag 29 mei 2016 10:37
> Aan: hecnet at Update.UU.SE
> Beantwoorden: hecnet at Update.UU.SE
> Cc: hecnet at Update.UU.SE
> Onderwerp: RE: [HECnet] VMS 5.4 backup
>
>> $define/translation=(concealed,terminal) foo _dua0:[what.ever.tapes.]
>> $backup/log/verify saveset foo:[*...]
>>
>> Note the trailing "." in the logical - don't omit that! Also notice that
>> you must use a physical device name in the logical definition.
>
> Thanks.
>
> Next problem, there is a read error on the tape, how do I tell backup
> to give up and continue with the rest of the save set, if possible?
>
>
> --P
>

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol