Date: Fri, 3 Dec 2004 14:24:15 +0000 From: Ceri Davies <ceri@submonkey.net> To: Ken Smith <kensmith@cse.Buffalo.EDU> Cc: freebsd-stable@freebsd.org Subject: Re: 4.x can't read 5.x dump? Message-ID: <20041203142415.GJ513@submonkey.net> In-Reply-To: <20041202024052.GA11786@electra.cse.Buffalo.EDU> References: <200412020048.iB20mhiP009447@app.auscert.org.au> <20041202024052.GA11786@electra.cse.Buffalo.EDU>
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--ZInfyf7laFu/Kiw7 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Dec 01, 2004 at 09:40:53PM -0500, Ken Smith wrote: > On Thu, Dec 02, 2004 at 10:48:43AM +1000, Joel Hatton wrote: >=20 > > I'm backing up a 5.x machine at the moment with this command: > >=20 > > dump -0Lau -b128 -f - /var | gzip -2 | ssh FreeBSD4 dd of=3Daacd0s1f.gz > >=20 > > After the dump finishes, I try to read the file on the 4.x destination: > >=20 > > # gzip -dc aacd0s1a.gz | restore -ivf - > > Verify tape and initialize maps > > Tape is not a dump tape > >=20 > > I can scp the file back to the 5.x machine and it loads just fine, so w= hat > > gives? This type of failure is somewhat scary for me right now, given t= hat > > I may have to restore files to another destination that may not be 5.x > > based. >=20 > This is, unfortunately, something that you should not expect to work > for any *nix variant. The dump mechanism of creating backups creates > output that has "intimate knowledge" of the filesystem so that it can > recreate that filesystem exactly as it exists on the disk. As the > filesystem itself evolves (has features added to it) the dump programs > need to have their data structures change to accomodate the extra > information that is now needed. For example if in 4.X there were no > ACLs but 5.X added ACLs then the dump program's data structures would > need to be changed so it had the ability to store the ACL information > in the output, and the restore program would need to be modified to > look for that and do the right thing if it finds ACL information. >=20 > If there had been no filesystem changes between 4.X and 5.X then > there would not be any need to change dump, and what you are trying > to do would work. But there were filesystem changes between 4.X and > 5.X, so dump was changed, and now there is extra stuff in the dump > images that the 4.X version of restore doesn't understand. This same > general principle holds for all OS's, not just FreeBSD. Should I expect a dump taken from 4.X to be restorable on 5.X though? (I do). Ceri --=20 Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Einstein (attrib.) --ZInfyf7laFu/Kiw7 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.6 (FreeBSD) iD8DBQFBsHcPocfcwTS3JF8RAki2AKCfpCezeMNrPhWbe6NGtc88mC7UrACdFX5G +znMGrErtK6h8FG+9BTzQnY= =fhtO -----END PGP SIGNATURE----- --ZInfyf7laFu/Kiw7--
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