OT: rsync on Mac OSX

[Chris Maness]

On Fri, Jul 12, 2013 at 11:12 AM, Paul Kraus <paul at kraus-haus.org> wrote:

> Dropping the list …
>
> On Jul 12, 2013, at 1:49 PM, Chris Maness <chris at chrismaness.com> wrote:
>
> > Checksums are the same.  All other files still work however the HUGE
> > rendered Final Cut Pro output, so I guess it is something in .DS_Store.
> > Last time I just gave up and recopied everything by a simple cut and
> paste
> > and that solved the problem.  I made a small change on the project today,
> > and I don't want to have to copy the WHOLE thing again just for a small
> > delta.  I already synced the directories, but the new rendered files are
> > still un-openable in any application even though the checksums match.
> > Really weird.  However, the project will still open and work on FCP.
>  Just
> > the 12Gb rendered movie files will not play on anything even FCP.  If I
> > delete .DS_Store will the system regenerate it with the appropriate file
> > associations?
>
> The .DS_Store files are created by the Finder when you view a directory.
> Are both source and destination on Mac HFS+ volumes ? If so, then you are
> probably missing the resource forks.
>
> Back in the very old days of Mac OS (way before 10.x), Mac OS files had
> two parts, the data part that contained the, well, data, and the resource
> fork that contained the meta-data that Mac OS used to associate a file with
> an application. HFS+ volumes on Mac OS X still include the resource forks,
> but "foreign" filesystems (NFS, UFS, FAT, etc.) do not. The work around
> that Apple came up with is to create .DS_Store and ._<foo> files to store
> this metadata on non HFS+ volumes.
>
> You could try using ditto instead of rsync. ditto is a BSD derived copy
> utility similar to rysnc, but I know that the Mac OS X version understands
> resource forks and copies them as necessary. ditto may not be able to just
> copy changed blocks within a file, so you may still have to recopy the
> entire file.
>
> But…. I am also a little puzzled because applications on Mac OS X do not
> NEED the resource fork to open a file, just to know which application to
> use (and what options to hand it) to open a given file. A complete video
> file, even without resource forks, should be able to be opened if you
> explicitly telly he application to File -> Open …. With the checksums
> matching it is even odder. I expect that the large sizes (over 4 GB) are a
> contributing factor.
>
> Good luck and let me know what you find.
>
> --
> Paul Kraus
> Deputy Technical Director, LoneStarCon 3
> Sound Coordinator, Schenectady Light Opera Company
>
>
Thank you for the detailed description of what resource forks are.  One
more clue in this mystery is that appending .mov extension to it fixes the
problem.  I have never ran into this before, and I have even used rsync to
back up movie projects before.  It is not a big deal, but I always try to
take the time to understand why things behave the way they do.  I also
suspect it has something to do with file size since all of the smaller
files do not have this issue.

Thanks,
Chris Maness