Mini-HOWTO: Fixing rsync on Tiger (Mac OS X 10.4.x)

J.D. Bakker jdb at
Mon Nov 28 03:25:30 GMT 2005

[Now the horse has left the barn, I decided to finally implement that 
backup system I'd been thinking about for ages. Disk crashes can be 
great motivators]

[Web-location for the living version of this document:]


Producing a working network backup / cloning system for Mac OS X 
systems. The system can be used for local backups as well, for 
example to FireWire disks.


Many files on HFS+, the Mac's most common file system, have metadata. 
This is partly a leftover from the past (resource forks), and partly 
a new development (ACLs, extended attributes). Plain rsync doesn't 
(yet) cope with this metadata.

Since OS X 10.4 (aka Tiger) the MacOS ships with a modified version 
of rsync. An added option, '-E', enables the transfer of extended 
attributes. This is done by encapsulating the resource fork, Finder 
data et al in a synthetic file which is added to the rsync transfer 
list. The name of this file is formed by prepending '._' to the name 
of the original file, a technique which is also used when copying 
data from HFS+ partitions to non-Apple file systems such as NFS 
mounts. It may not be pretty or foolproof (what happens when both foo 
and ._foo exist?), but at least it's documented by Apple and lot 
likely to change in the very near future. This rsync derivative is 
based on rsync-2.6.3.

However, Googling and testing have revealed four problems with 
Apple's rsync. In order of severity, worst first:

1) The rsync sender will frequently crash with a Bus Error / 
Segmentation Fault after generating the file list, but before 
transferring any files. This turns out to be caused by a buffer 

2) When used with the --delete option, the rsync receiver will try to 
unlink the (fake) synthetic files, flooding the syslog with failure 
reports, possibly filling the entire boot disk.

3) When files with extended attributes are transferred, the 
modification time will be set to the time of the transfer, even when 
the user has specified that modification times be preserved. As a 
result, using mtime to determine whether a file has changed is broken.

4) Extended attributes have no modification time of themselves. Since 
a file's mtime is not updated when its attributes are changed, only 
checksumming can be used to determine whether attribute data needs to 
be transferred. With default settings, this means that ALL extended 
attributes are ALWAYS copied.

The patch:

Problems 1-3 are fixed by the patch at . This patch is 
released under version 2 of the GNU GPL. I know of no fix for problem 
4, but consider it mostly an annoyance.

Putting it all together:

NOTE: This requires familiarity with the Terminal. I have no .dmg or 
whatnot, since I wouldn't know how to create one (and there are 
licensing issues, see below). Following these steps should get you a 
working rsync, though.

0) Update Tiger to 10.4.2. Install XCode, the Apple developer tools. 
If you don't have the disc (it's shipped with the Tiger install 
media), you can get the latest version from Apple's developer website 
(free registration required):

1) Get the sources. Open the terminal, and type:

   mkdir rsync-build
   cd rsync-build
   curl -O
   curl -O
   curl -O
   curl -O

2) If you don't already have it, install copyfile.h in /usr/include . 
Get it from Apple's developer website 
(again, free registration required). In the Terminal:

   sudo mv -n copyfile.h /usr/include

Copying to /usr/include requires root privileges; enter your password 
when prompted. The '-n' option to mv makes sure that you don't 
overwrite a (newer) installed version.

NOTE: copyfile.h is *NOT* licensed under the GPL, but rather under 
the Apple Public Source Licence 
( You may want to review this 
license; I Am Not A Lawyer so I cannot say and will not speculate on 
how this affects your rights.

4) Unpack the rsync source, and apply the patches. In the Terminal:

   tar zxf rsync-2.6.3.tar.gz
   cd rsync-2.6.3
   patch -p0 < ../EA.diff
   patch -p0 < ../PR-3945747-endian.diff
   patch -p0 < ../rsync-tiger-fixes.diff

5) Configure and make rsync:

   ./configure --enable-ea-support

6) You now have a patched rsync binary. If you're feeling brave, you 
can replace the Apple-supplied version with it (sudo cp -f rsync 
/usr/bin). Myself, I'd suggest installing it in /usr/local/bin (the 
default) by doing:

   sudo make install

Note that this procedure is for a plain XCode install. If you're 
using Fink you'll need to change bits (but then, you'll probably know 

As is documented on other sites, you'll want to make sure that the 
target drive has 'Ignore Ownership on This Volume' DISABLED 
(Finder:Get Info on the disk, the button is under the 'Ownership & 
Permissions' - tab). Also, it helps to turn Spotlight off for the 
target volume.

Bottom line:

It Works For Me. I've run a few tests, both full and incremental, 
with ~60GB in just over half a million files with creation dates 
going back to 1994 (Pathways into Darkness, anyone ?). With rsync 
installed in Server mode (see the man pages) on a Mac mini, a 
no-changes full filesystem 'incremental' backup takes 45 minutes over 
Airport Extreme (and less over Ethernet), during which both machines 
are still mostly responsive. For reference, my command line is:

sudo ./rsync/rsync-2.6.3-jdfix/rsync -aREx --delete 
--exclude='.Spotlight-*' --exclude '/private/var/vm/*' / [IP-address 
of Mac mini]::PowerBookBackup

I have successfully booted the Mac mini from the resulting disk 
clone. Although I haven't stress-tested the system, all looked well 
(I could open Photoshop and iTunes with no problems). A similar 
procedure should work to an external disk attached to the source 
computer, although I haven't tested that configuration.

So why didn't I just use RsyncX ? Googling revealed some (perceived?) 
compatibility issues between RsyncX and Tiger. Besides, RsyncX only 
works between Macs, and I *really* want to use my 1.5TB RAID-5 Linux 
box as backup target.

About the rsync -H option: there have been rumors of incompatibility 
with OSX. I'll have to find out; however, on my PowerBook's boot 
drive only 4050 of the >500000 files have a link count greater than 

These bugs and fixes have been reported to Apple.

What's next:

Getting rsync-on-X to play nice with rsync-on-Linux.
Porting all patches to rsync-2.6.6.

DISCLAIMER: No warranties whatsoever. Do not ever trust a backup 
system you haven't thoroughly tested. I know that I claim it's 
working, but I might be lying or hallucinating (or missing important 

I have tried to include all information which I'd hoped to find in 
one place when I started this journey a few days ago. Hope it's of 
some use to others.

[as they say: you'll get experience right after you needed it]
LART. 250 MIPS under one Watt. Free hardware design files.

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