>... why can't tape
>operations happen while the dump to the holding disk is happening? ...
They already do. What does that have to do with not repositioning the
tape at all?
>Now, am not 100% certain on how taper does write the files to tape ...
Very quick review:
Rewind
Read the label and verify
Rewind
Write a new label and tapemark
Write a header, image and tapemark
Write a header, image and tapemark
...
Write the trailing label, tapemark and quit (leaving the tape where it is)
(for the purists among you this is not strictly correct as the tapemark
is actually deferred until the start of the next writing, but this is
close enough for the purposes of this discussion).
>... Why not [save] the last one in tapelist, and/or amount of tape used?
That's the plan.
>so, now you are effectively doing an 'mt fsf <last field>' to get to end
>of tape ...
True. The problem is that the drive may screw up. You may tell it to
skip 37 files and it skips 36 (or 38, or 10, or 100 ...). So you have to
go somewhat short on the skip count, read the label to find out where you
really are, then (possibly) skip some more, or even rewind and start over.
>if you store the amount of tape saved to that tape, you would
>be able to pre-determine whether or not there is even any room left on
>that tape to be worth the effort ...
Agreed.
>Okay, not quite sure what the 'end marker' would be used for ...
If you're trying to skip to the end of a tape, you need to read something
good after that last fsf plea to the tape gods. If the device uses
double tape marks as EOM and you go too far, an evil reverse motion has
to happen. Or you might get an I/O error and not know whether it's a
real problem or just because you ended up where you wanted.
>if I do a
>dump to tape, using dump, onto the no-rewind device, and put n file
>systems onto that tape, there is no 'end marker' put onto the tape, is
>there? ...
No, but I don't understand the point.
>so, instead of an 'end marker', why not create a 'dummy dump' at
>the end of a tape ...
That's effectively what we have. After the last image is a tapemark
and then a single 32 KByte Amanda label. It's that label (end marker)
we will be hunting for to then start writing after.
>Marc G. Fournier
John R. Jackson, Technical Software Specialist, [EMAIL PROTECTED]
