Re: dump & restore
Here's the scoop. Dump wants to know how much capacity the tape has. Traditionally
this information was given to dump by passing it the density *and* length. Linux dump
allows you to specify the tape capacity in bytes with the 'B' option. Apparently some
very old tape systems could not detect the end of tape so this was important to dump
and as you've discovered dump is quite anal about stopping when it thinks the tape is
full. Now, after you've written one dump image of course the space left on the tape
will be less than the original capacity. However, since most modern tapes detect end
of file dump will fail with an error message that it reached the end of the tape. No
big deal. If it fails there wasn't anything you could have done about it anyway unless
you were around to get a different tape. I know that multi-volume backups did not work
with linux dump in the past. I'm not sure if this is fixed yet.
Mario Olimpio de Menezes wrote:
> I'm trying to learn how dump and restore utilities work and I'm
> having not much success. I could do a dump of a filesystem using the line
> dump 0udf 61000 /dev/nst0 /tmp2, where 61000 is the density of my tape.
> If I do only this, I can restore /tmp2 without problems.
> How can I backup another filesystem to the tape? It's a 60m tape;
> /tmp2 is only 190MB and the filesystem I want to append is about 300MB,
> that is, there is free space!
> I have read the man pages but couldn't figure out how to do this.
> Any help will be greatly appreciated. Suggestions on other methods
> of backup, too!
Jens B. Jorgensen
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