How-To: Time Machine Backup on a Network Storage

Again, I’m writing for convenience here (i.e. for personal reference in the future). There’s a bunch of more helpful posts on the topic out in the information jungle (the Internet). This post is a summary of the command that worked for me based on this macosxhints discussion.

It’s been a while, yes. But now I’m jumping into the bandwagon.

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To configure your machine to use Time Machine, go to System Preferences -> System -> Time Machine. Click on the slider to turn it on.

Then select the Disk to be used for backup. Normally, it will only detect local drives. If you are going to use network storage, like what i will do, make sure to issue this command. Time Machine should now list your network storage along with local disks.
defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1

Now this is the usual error i get. This is the culprit why i did not continue setting up Time Machine before. If like me, you encounter the message “The backup disk image could not be mounted” after a few minutes of “preparing”, then issue the ff. command:
hdiutil create -size $SIZEg -fs HFS+J -type SPARSEBUNDLE -volname "Backup of $HOSTNAME" $HOSTNAME_$MACADDR.sparsebundle

$SIZE is the size of the backup volume; the appending g is for GB, m for MB and so on..
$HOSTNAME is the computer name
$MACADDR is well, the mac address of the machine, without the colons. This is the same mac address of the ethernet card. To check, go to System Profiler -> Network -> Ethernet, then copy the mac address field.

Mount your network storage (as AFP in my case).  Then copy the file created above.

cp -r $HOSTNAME_$MACADDR.sparsebundle /Volumes/Backup/

Open Time Machine settings from System Preferences. Select the NAS Volumes as backup disk. Set Options to select which folders not to backup. Then you’re all set.

So that’s it. You’re done.

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UPDATE

Commands to use after changing the Logic Board:

cd /Volumes/Time Machine/Backups.backupdb
xattr -p com.apple.backupd.BackupMachineAddress MyMac

$ sudo fsaclctl -p /Volumes/Time Machine -d
$ sudo mv .00f9e8d7c6b5 .001a2b3c4f56
$ sudo xattr -w com.apple.backupd.BackupMachineAddress 00:1a:2b:3c:4f:56 Backups.backupdb/MyMac
$ sudo fsaclctl -p /Volumes/Time Machine -e

Note: This doesn’t seem to work for NAS. One reason probably is the mac address of the Sparse Bundle. I’ll give it another go sometime.