10.6: Set up Time Machine on networked AFP volume

The upgrade to Snow Leopard breaks 10.5.x Time Machine backups configured with AFP shares on network volumes, as per this older hint, for example.

After some trial and error, I was able to find out that the secrect lies with a hidden property list file that specifies the hardware UUID for the machine to be backed up. The following are some simple instructions to set up a new backup volume from scratch. They may work for upgrading a Leopard Time Machine disk to Snow Leopard, but I have not been able to verify this.

Setup: If your Time Machine is already configured to back up to a networked AFP share, move on to the next step. Otherwise, follow the setup procedure in the above-linked hint.

Simple method: Use the script and directions that I posted on the InsanelyMac forums.

Manual method:

Create a disk image named the same as your machine's computer name (not sure that this is crucial; you can find it in System Preferences » Sharing). This example is for a 500GB (max size) image for a machine named snowy:

hdiutil create -size 500G -fs HFS+J -volname 'Time Machine Backups' -type SPARSEBUNDLE snowy.sparsebundle

Create a new text file, and copy and paste the below code. inserting your machine's hardware UUID in the noted spot -- you can find your hardware UUID in System Profiler. Save the file on your Desktop as com.apple.TimeMachine.MachineID.plist.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>com.apple.backupd.HostUUID</key>
    <string>YOURUUIDHERE</string>
</dict>
</plist>

Copy the modified com.apple.TimeMachine.MachineID.plist file into your disk image directory: cp ~/Desktop/com.apple.TimeMachine.MachineID.plist snowy.sparsebundle/
Copy your disk image file to your mounted backup volume. This example assumes an AFP share with the name backups: cp -pfr snowy.sparsebundle /Volumes/backups/snowy.sparsebundle

Please let me know if you run into any issues.

[robg adds: I haven't tested this one.]

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10.6: Set up Time Machine on networked AFP volume | 11 comments | Create New Account

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10.6: Set up Time Machine on networked AFP volume
Authored by: everkleer80 on Thu, Sep 24 2009 at 9:12AM PDT

Strange, I believe the TM backup from my MacBook to an AFP share on my iMac still works after the SL upgrade.

This is interesting though... so it looks like the backup doesn't need to be dependant on your MAC address anymore?

10.6: Set up Time Machine on networked AFP volume
Authored by: sunkid on Fri, Sep 25 2009 at 7:15AM PDT

Yes, OSX-based shares (> 10.4) seem to work out of the box.

btw - I am the author of the hint :)

10.6: Set up Time Machine on networked AFP volume
Authored by: zzz99 on Thu, Sep 24 2009 at 9:23AM PDT

The .sparsebundle I have is 145MB, is that correct? I have also change the backup size to 30GB instead of 500GB.

Overall, this method doesn't work in my case.
------------------------------

Hi everkleer80,

I was in the same suitation as you, until I have done 2nd clean install for Snow Leopard, then I start getting this message.

http://dl.getdropbox.com/u/266708/AirportExtremeProblem-1.png

10.6: Set up Time Machine on networked AFP volume
Authored by: stcanard on Thu, Sep 24 2009 at 9:24AM PDT

It works for me, with a caveat:

Every time I reboot it breaks. I have to go back and do the following:

1) Modify the plist file again
2) Mount and unmount the disk image

And backups works again until the next reboot. If anybody has a solution for this, I'd love to hear it!

10.6: Set up Time Machine on networked AFP volume
Authored by: sunkid on Fri, Sep 25 2009 at 7:29AM PDT

That is strange behavior! Does your hardware UUID change between reboots? What system are you running on and what OS are you using to serve the AFP share?

10.6: Set up Time Machine on networked AFP volume
Authored by: tgarons on Thu, Sep 24 2009 at 5:46PM PDT

The title on this should be changed to "Non-Mac" networked volumes as mentioned in the original hint. I am successfully continuing to backup a couple of macbooks to an external disk on an imac with no changes needed.

Non-Apple AFP can be dangerous with time machine...
Authored by: dbs on Thu, Sep 24 2009 at 11:58PM PDT

Everyone should be aware that using Time Machine on a Non-Apple AFP volume via these hints may put their backup data at risk. Here's why:

The technical reason why Apple limits Time Machine to 10.5+ AFP volumes appears to be to prevent disk image corruption. There were additional features added to AFP in 10.5 to support Time Machine. These presumably allow the disk image engine to force disk image journal data to write out all the way to the disk. Without such features, a network interruption can result in a corrupted filesystem on the disk image despite journaling. Remember, journaling relies on the journal being written all the way to disk before the changes take place. If you can't guarantee that (e.g., because of network/NAS buffering) then the journal is useless. Time Machine appears to rely heavily on disk journaling to deal with network drop-outs, interrupted backups, and the like. Take this away and your data is at risk.

If the NAS you are using supports these features it should report them to the OS and you should natively be able to choose that volume. If you have to trick the OS to use the volume it means the NAS does not support it.

To summarize: if you care about your backup data you should avoid using non-natively supported AFP servers.

(There is a less-than-satisfactory work-around: backup to a Mac, then use rsync to copy the disk image to the NAS manually. This is what I do to have an off-site copy of my backup.)

[ Reply to This | # ]

Non-Apple AFP can be dangerous with time machine...
Authored by: sunkid on Fri, Sep 25 2009 at 9:47AM PDT

Thanks for the caveats! Can you clarify whether a network interruption would lead to a corrupted disk image or just to a corrupted backup?

There is also another issue users should be aware of that has to do with the size of the disk containing your backup image.

That said, I have a couple of backups to non-OSX based AFP shares running successfully now for about a year and I have not yet had any problems. One of these is from a laptop over WiFi with many of the backups interrupted due to the laptop being put to sleep.

[ Reply to This | # ]

10.6: Set up Time Machine on networked AFP volume
Authored by: Zim on Sun, Sep 27 2009 at 8:08AM PDT

My MacBook (running 10.6) backs (via TM) up to a networked AFP share on my linux box... NO change was needed for me from 10.5 to 10.6.

10.6: Set up Time Machine on networked AFP volume
Authored by: sunkid on Tue, Sep 29 2009 at 12:34PM PDT

That's interesting! What linux distro and AFP version are you using? Do you see any AFP related error messages in the system log? (I get a lot of '4F'-related errors, but they were there before as well)

10.6: Set up Time Machine on networked AFP volume
Authored by: macdebian on Fri, Dec 25 2009 at 12:15PM PST

I'm running OSX 10.6 and trying to get Time Machine to back up to a fileserver running Debian Lenny with netatalk and avahi. The target Debian filesystem is HFS+ and was created with the mkfs.hfsplus command from the hfsprogs package. Netatalk was patched using this trick:
http://blog.damontimm.com/how-to-install-netatalk-afp-on-ubuntu-with-encrypted-authentication/

I followed the instructions in the current hint for creating a sparsebundle with the .com.apple.TimeMachine.imacml.plist file as specified. It still doesn't work.

The backup volume shows up in the finder and can be mounted. I can copy files from the Mac to the Debian fileserver. However, Time Machine fails with an error 45. On the Debian side, the syslog shows afpd errors 4F and 4C.

Does anyone know how to solve this problem?

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