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Resource Forks...
Authored by: Mechanist on Sep 28, '07 04:31:50PM

Unfortunately resource forks are still quite common on Mac OS X. As far as I've been able to determine, this scheme won't back them up. That's not much of a surprise given that not many Unix tools take resource forks into account (except for the modified versions Apple has included on Mac OS X). Before considering a scheme like this you should really consider whether this limitation would be a problem for you.



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Resource Forks...
Authored by: sjk on Sep 28, '07 05:27:13PM
Before considering a scheme like this you should really consider whether this limitation would be a problem for you.
In some cases it can be difficult to accurately determine whether or not preserving resource forks is necessary. And even if it's not an issue now it might unexpectedly become one in the future. For me it's been easier having backup strategies that always preserve them to avoid unforeseeable problems if they weren't.

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Resource Forks...
Authored by: pxb on Sep 29, '07 01:01:29AM
Hi,

thanks for the warning about resource forks. On the duplicity website (http://duplicity.nongnu.org/new_format.html) they mention it being a limitation of the tar format it uses. However, the tar on OSX 10.4 is supposed to support Resource Forks, though whether this happens with the version of tar that duplicity uses, I don't know at present. I'll do some more research. I guess the simplest way would be to backup a file with known resource fork data and see what happens.

pxb

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Resource Forks...
Authored by: Mechanist on Sep 29, '07 04:28:16PM

As far as I know it's correct that the tar file format doesn't support resource forks. What the Mac OS X version of tar does is transparently convert files with resource forks to "AppleDouble" format, which just means that the resource fork gets put into the data fork of a secondary file. So if foo.jpg has a resource fork, the tar file contains foo.jpg with no resource fork as well as ._foo.jpg, which is a data-fork file containing the resrouce-fork info. When you extract the file the forks are restored.

If duplicity makes use of the on-board Mac OS X version of tar then it should be OK for resource forks, but if it builds the files some other way then it probably isn't.



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Resource Forks...
Authored by: asparria on Sep 30, '07 10:14:58AM
I use Backup Bouncer (http://www.n8gray.org/blog/2007/04/27/introducing-backup-bouncer) to test backup reliability. It checks resource forks, hard links, ownership, pipes, BSD flags, etc...

Just check it out and see if your backup software solution is as good as it seems.

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Resource Forks...
Authored by: pxb on Oct 16, '07 02:43:31PM

Thanks for the link. I'll use it to check if my backups are copying what I need



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