Re: [rdiff-backup-users] FreeBSD and xattr OS X support

[Will Prater]

On Oct 30, 2006, at 4:27 PM, Andrew Ferguson wrote:

> Will Prater wrote:
> > I do have a bizarre setup.  I have a NAS that all our mac clients
> > save their data too, they are saving over AFP and the Infrant NAS
> > seems to support the Resource Forks.  I NFS mount the NAS to my
> > backup server when backing up.
> >
> > I was hoping for a way to force the features on.
>
> If the Macs are saving to the NAS using AFP, then "seems" to support
> resource forks is not quite the same as actually supports resource
> forks. Resource forks are part of the filesystem -- if the NAS is  
> using
> HFS+ as its filesystem then it would actually support resource forks.
>
> If it does not use HFS+ as its filesystem (much more likely), then AFP
> will map the resource fork data to ._ files upon copying the data  
> to the
> NAS. When the file is copied back from the NAS, AFP will look for the
> corresponding ._ file and read its contents into the copied file's
> resource fork. Here, the resource fork is stored as a regular file and
> when you mount the files over NFS on your backup server, the ._ files
> should be there as well and rdiff-backup should be merrily copying  
> them.

Very informative and good information to know.  Thank you.

I feel safe with my current backup strategy.

> > > Extended attributes are file attributes at the filesystem level. I
> > > know
> > > ext3fs has them (but you need to explicitly turn them on as a mount
> > > option) and the Mac HFS+ filesystem has them. The python module
> > > pyxattr
> > > (http://pyxattr.sourceforge.net/) supports them for ext2/ext3 or
> > > XFS on
> > > Linux and the python module xattr (http://undefined.org/python/)
> > > supports them for HFS+ on Mac OS X.
> >
> > Is there no way to force this on a FreeBSD system then?
>
> It turns out extended attributes were introduced as part of FreeBSD  
> 5.0
> (see http://www.freebsd.org/cgi/man.cgi?query=extattr&format=html).  
> The
> second of those two Python modules added FreeBSD support in September.
> You can get it from http://undefined.org/python/ -- scroll down to
> xattr. Install that, and you should see extended attributes support  
> turn
> on in rdiff-backup.
>
> I can't tell if FreeBSD's extended attributes depend on the underlying
> filesystem, or are implemented at the virtual filesystem (VFS) layer.
> Note also that since your backup target is mounted over NFS, whether
> there *are any* extended attributes to be backed up depends on 1) the
> NAS and 2) the NFS setup exposing them.

I tried for a bit to get the python module installed, but its not  
worth it to me.  Sounds like there will be no negative effects to my  
current process, if they are restored correctly.


-Will