question on extended attributes

[Rick Macklem]

> On Apr 15, 2011, at 7:01 PM, Jeremy Chadwick wrote:
> 
> > On Fri, Apr 15, 2011 at 05:01:58PM -0500, Daniel Mayfield wrote:
> >> I'm trying to use rsync and rsnapshot to make backup copies of my
> >> Mac to my freebsd 8.2 server . When I specify syncing extended
> >> attributes as well, I get an error for any file on the Mac that has
> >> a resource fork:
> >>
> >> rsync: rsync_xal_set:
> >> lsetxattr("Documents/<foo>","com.apple.ResourceFork") failed: No
> >> space left on device (28)
> >>
> >> I'd love to work on fixing this, but I'm seeing a bunch of
> >> references to UFS1 vs UFS2 in the extended attribute readme. But
> >> I'm not sure what I'm actually using (I took the default when it
> >> setup, which says ufs2+softdep, but mount simply says ufs).
> >>
> >> Can someone help point me in the right direction?
> >
> > Sorry if this sounds harsh or rude, but can I ask you what exactly
> > extended filesystem attributes (usually ACLs) have to do with file
> > resource forks on OS X? AFAIK they have nothing to do with one
> > another.
> 
> OS X stores resource forks (and a few other things) as extended
> attributes on HFS+ filesystems these days. Or at least that's how it
> presents the HFS+ concept of a resource fork to unix programs like
> rsync that understand extended attributes.
> 
> > Also, you're aware of how Apple solved the resource fork problem
> > when
> > archiving something in a .zip file, right? The "_MACOSX" directory
> > within the .zip.
> 
> This is sub optimal as I'd like to be able to inspect/modify the "data
> fork" of the file on the freebsd box too. For example, editing files
> while I'm ssh'd into the freebsd machine remotely, but still
> preserving the icon when it gets copied back. If I were to do as you
> described, I may as well setup netatalk and build a time machine style
> backup device. That isn't my goal.
> 
I don't believe that resource forks are available under FreeBSD at this
time. Solaris supports the "subfile" concept, which is basically the same
as far as I know, so it seems there might be something inside ZFS, although
I suspect it isn't available for FreeBSD?

Does anyone familiar with ZFS know more?