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As regular readers saw earlier, I've been casting about trying to find an open source backup solution that handles OS X metadata reliably. Having been disappointed by rdiff-backup, I've turned by eyes to the similar rsnapshot project, which uses the venerable rsync.

Since macports includes the latest version of rsync, 3.0.2, I gave it a try with the familiar rsync -avz /from /to syntax, but it performed disappointingly on n8's handy Backup Bouncer test suite. Thanks to Mike Bombich, I learned about some extra flags to add (though my copy of rsync doesn't seem to know about the -N or --fileflags he has):

$ sudo rsync -aHAXx  /Volumes/Src/ /Volumes/rsynctest/
$ ./bbouncer verify -d /Volumes/Src/ /Volumes/rsynctest/
Verifying:    basic-permissions ... ok
Verifying:           timestamps ...
   Sub-test:    modification time ... ok
ok
Verifying:             symlinks ... ok
Verifying:    symlink-ownership ... ok
Verifying:            hardlinks ... ok
Verifying:       resource-forks ... ok
Verifying:         finder-flags ... ok
Verifying:         finder-locks ... FAIL
Verifying:        creation-date ... FAIL
Verifying:            bsd-flags ... FAIL
Verifying:       extended-attrs ...
   Sub-test:             on files ... ok
   Sub-test:       on directories ... ok
   Sub-test:          on symlinks ... ok
ok
Verifying: access-control-lists ...
   Sub-test:             on files ... ok
   Sub-test:              on dirs ... ok
ok
Verifying:                 fifo ... FAIL
Verifying:              devices ... FAIL
Verifying:          combo-tests ...
   Sub-test:  xattrs + rsrc forks ... ok
   Sub-test:     lots of metadata ... ok
ok

Sure, there are a few FAILS in there, but they're not important:

$ ./bbouncer verify -T important -d /Volumes/Src/ /Volumes/rsynctest/
Verifying:    basic-permissions ... ok
Verifying:           timestamps ...
   Sub-test:    modification time ... ok
ok
Verifying:             symlinks ... ok
Verifying:            hardlinks ... ok
Verifying:       resource-forks ... ok
Verifying:         finder-flags ... ok
Verifying:       extended-attrs ...
   Sub-test:             on files ... ok
   Sub-test:       on directories ... ok
   Sub-test:          on symlinks ... ok
ok
Verifying: access-control-lists ...
   Sub-test:             on files ... ok
   Sub-test:              on dirs ... ok
ok

(note the -T important flag telling Backup Bouncer to remove the extra-finicky tests). Good enough! On to get familiar with rsnapshot.

I've finally had the chance to repeat my test of the rdiff-backup-devel package from MacPorts, using the same steps as I used for the stable package. The results are better but not fantastic:

$ ./bbouncer  verify -d /Volumes/Src/ /Volumes/rdifftest
Verifying:    basic-permissions ... ok
Verifying:           timestamps ...
   Sub-test:    modification time ... ok
ok
Verifying:             symlinks ... ok
Verifying:    symlink-ownership ... ok
Verifying:            hardlinks ... ok
Verifying:       resource-forks ... ok
Verifying:         finder-flags ... FAIL
Verifying:         finder-locks ... FAIL
Verifying:        creation-date ... ok
Verifying:            bsd-flags ... FAIL
Verifying:       extended-attrs ...
   Sub-test:             on files ... ok
   Sub-test:       on directories ... ok
   Sub-test:          on symlinks ... FAIL
FAIL
Verifying: access-control-lists ...
   Sub-test:             on files ... FAIL
   Sub-test:              on dirs ... FAIL
FAIL
Verifying:                 fifo ... ok
Verifying:              devices ... ok
Verifying:          combo-tests ...
   Sub-test:  xattrs + rsrc forks ... ok
   Sub-test:     lots of metadata ... FAIL
FAIL

With promising reports out on rsync 3, looks like it's time to take another look at rsnapshot...

Preamble: after a bunch of research, rdiff-backup looked like a good open source solution for OS X backup. And it's in macports!

Wrinkle: after getting further into my current backup project, I've become more aware of the difficulty of getting all of the various forms of OS X metadata backed up. Some research revealed the tool Backup Bouncer, which provides a way to run some tricky tests on any OS X backup system. Here I'm using the latest bbouncer (0.1.2), on a 10.4.11 system all patched up through security update 2008-03.

The stable version of rdiff-backup in macports is 1.0.5, which is what's being used for the following tests. I've poked at both this and the rdiff-backup-devel version, which is 1.1.15, but it doesn't automatically pull in the xattr module from macports. I'll retest with that version later. Also note that the bbouncer results don't suggest that xattr is doing 1.0.5 much good.

$ ./bbouncer create-vol rdifftest
$ sudo rdiff-backup /Volumes/Src /tmp/bb
$ sudo rdiff-backup --force -r 1D /tmp/bb /Volumes/rdifftest/
$ ./bbouncer verify -d /Volumes/Src/ /Volumes/rdifftest/
Verifying:    basic-permissions ... ok
Verifying:           timestamps ...
   Sub-test:    modification time ... ok
ok
Verifying:             symlinks ... ok
Verifying:    symlink-ownership ... ok
Verifying:            hardlinks ... ok
Verifying:       resource-forks ... FAIL
Verifying:         finder-flags ... FAIL
Verifying:         finder-locks ... FAIL
Verifying:        creation-date ... FAIL
Verifying:            bsd-flags ... FAIL
Verifying:       extended-attrs ...
   Sub-test:             on files ... FAIL
   Sub-test:       on directories ... FAIL
   Sub-test:          on symlinks ... FAIL
FAIL
Verifying: access-control-lists ...
   Sub-test:             on files ... FAIL
   Sub-test:              on dirs ... FAIL
FAIL
Verifying:                 fifo ... FAIL
Verifying:              devices ... FAIL
Verifying:          combo-tests ...
   Sub-test:  xattrs + rsrc forks ... FAIL
   Sub-test:     lots of metadata ... FAIL
FAIL

That's a whole lot of FAIL, especially compared to the built-in OS X rsync, which passes on resource forks and finder flags, extended attributes for files and directories, ACLs, and the last few tests.

Granted, there are a bunch of things being tested by bbouncer that may or may not be of interest to the average user. A recent post by the author points out that bbouncer has a -T flag for indicating which level of paranoia to run at. Rerunning the test for rdiff-backup 1.0.5 with only critical tests is somewhat instructive:

$ ./bbouncer verify -d -T critical /Volumes/Src/ /Volumes/rdifftest/
Verifying:    basic-permissions ... ok
Verifying:           timestamps ...
   Sub-test:    modification time ... ok
ok
Verifying:             symlinks ... ok
Verifying:       resource-forks ... FAIL
Verifying:         finder-flags ... FAIL

Compare to OS X's rsync:

$ ./bbouncer verify -d -T critical /Volumes/Src/ /Volumes/Dst/10-rsync-apple/
Verifying:    basic-permissions ... ok
Verifying:           timestamps ...
   Sub-test:    modification time ... ok
ok
Verifying:             symlinks ... ok
Verifying:       resource-forks ... ok
Verifying:         finder-flags ... ok