how to append multiple dumps to single tape

[Malcolm Kay]

On Tue, 16 Dec 2003 12:46, DG wrote:
> On the subject of multiple dumps, how does one append several dumps to the
> same tape?  The dump man page does not seem to indicate an 'append' option.
>

When you open a tape for writing (or reading) then writing (or reading) begins 
at wherever the tape happens to be positioned. So one just has to ensure that 
the tape is not rwound after the first dump is written. This is achieved by 
writing the first dump to device /dev/nsa0 (or some other beginning with 'n'
which means no re-wind on close).

If the tape has been rewound (perhaps to remove the cartridge for storage)
then you can reposition the tape using 'mt fsf' followed by the number of 
dumps already written to the tape.

If a tape has been used a number of times there is no way for the system to 
reliably distinguish the end of the valid information from futher junk that 
may have been written in previous use -- thus for normal tape drives an
'append' command would be quite flakey.

Malcolm Kay