4.x can't read 5.x dump?

Nick Barnes Nick.Barnes at pobox.com
Thu Dec 2 03:56:02 PST 2004

At 2004-12-02 02:40:53+0000, Ken Smith writes:
> On Thu, Dec 02, 2004 at 10:48:43AM +1000, Joel Hatton wrote:
> > I'm backing up a 5.x machine at the moment with this command:
> > 
> > dump -0Lau -b128 -f - /var | gzip -2 | ssh FreeBSD4 dd of=aacd0s1f.gz
> > 
> > After the dump finishes, I try to read the file on the 4.x destination:
> > 
> > # gzip -dc aacd0s1a.gz | restore -ivf -
> > Verify tape and initialize maps
> > Tape is not a dump tape
> > 
> > I can scp the file back to the 5.x machine and it loads just fine, so what
> > gives? This type of failure is somewhat scary for me right now, given that
> > I may have to restore files to another destination that may not be 5.x
> > based.
> This is, unfortunately, something that you should not expect to work
> for any *nix variant.

There's no theoretical reason why the formats used by dump and restore
shouldn't be forward and backward compatible, allowing an older
restore (to an older filesystem type) to pick out the parts of the
dump which make sense to it while ignoring parts which it doesn't

But they aren't, so it can't, so you're out of luck.

[In theory, the filesystem could package itself, so an old restore
 binary running on a newer filesystem and given a newer dump would

Bikeshed, bikeshed.

Nick B

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