Mac – How to enable Time Machine to backup the data ON an SD Card? (NOT backup TO an SD card)

backupsd cardtime-capsuletime-machine

Time Machine does not allow the inclusion of an SD Card in a backup. It is automatically listed in the exclusion list and cannot be removed.

Is there any way to force Time Machine to 'see' the SD Card and back it up?

I use a 128gb SD Card as additional storage in my MacBook Air and would like to have the data on it automatically backed up to my Time Capsule.

Best Answer

Three things will need to come together for this to work:

The Filesystem on the SD card needs a .fseventsd hidden directory and the system to track all changes (which typically gets created automagically when you format the card as HFS+) I haven't seen anyone hack Time Machine to back up filesystems that don't register with Apple's file system events API.
Make a test backup once you've gotten the filesystem into one that Time Machine supports. You can then check if /Volumes/SD is included in the files for that backup by inspecting the preferences for that backup
If you need to manually include the system, you can add it by changing either the metadata flag that is causing the item to be skipped or by editing the system exclusion lists.

You will need to pick parts of these two questions and answers to find both the settings for a specific backup as well as where the various system exclusion rules are stored and configured.

In short, it might be easier to use rsync or some other tool to copy the SD card contents to a drive that already is being backed up, but as long as you have total control over the drive and the system, you should be able to bend it to your will and get the SD card to be seen and backed up every time it's present and a backup happens.

Modes and ownership

Ideally, use chmod(1) and chown(8) to have the mode and ownership, of the copy of the disk image, consistent with how Mountain Lion normally creates a local disk image for Time Machine.

Example

GPES3E-gjp4-1:~ gjp22$ sudo ls -al /Volumes/tall/com.apple.backupd/GPES3E-gjp4-1.sparsebundle/
Password:
total 16672
drwx------@ 3 root   staff     10  7 Jun 19:07 .
drwxr-xr-x  8 gjp22  staff     10  6 Jun 18:57 ..
-rw-r--r--  1 root   staff    500  7 Jun 18:03 Info.bckup
-rw-r--r--  1 root   staff    500  7 Jun 18:03 Info.plist
drwx------  2 root   staff  78855  7 Jun 19:07 bands
-rw-r--r--  1 root   staff    444  7 Jun 18:02 com.apple.TimeMachine.MachineID.bckup
-rw-r--r--  1 root   staff    444  7 Jun 18:02 com.apple.TimeMachine.MachineID.plist
-rw-r--r--  1 root   staff   1473  6 Jun 21:28 com.apple.TimeMachine.Results.plist
-rw-r--r--  1 root   staff  10698  6 Jun 22:24 com.apple.TimeMachine.SnapshotHistory.plist
-rwx------  1 root   staff      0 19 Mar 19:36 token

– and for each band, you should have:

-rw-------  1 root  staff

Attaching the copy of the disk image

With Terminal, for the example above:

sudo hdiutil attach -readonly /Volumes/tall/com.apple.backupd/GPES3E-gjp4-1.sparsebundle/

If you use Terminal from within Recovery OS: you'll probably not need the sudo prefix to the command.

Additional detail

… whether I can still restore …

You require:

a copy of a Time Machine destination, a copy that will be good for restoration
not an additional Time Machine destination.

Assumption

You wish the copy to be usable, for restoration only, in the event of loss or failure of the Time Capsule.

If the disk is attached from a local image where modes and ownership vary from the norm for a local image:

OS X or Recovery OS might use that disk without difficulty; I can't be certain.

Thoughts

If you're preparing for the possibility of loss or failure of a Time Capsule – and restoration from a copy of what was there – then think a step further, to backing up without the original Time Capsule. (If you wish the copy to be writeable by Time Machine, that could be a separate question.)

All things considered

It's probably quicker and simpler to use the external hard disk, or a part, as a Time Machine destination.

MacBook – Time machine/capsule read-only error

Read only is a fail safe mode for the backups. It means there was a problem detected with the backup and you can only restore from it.

The system won't continue adding files since that would risk your losing even the ability to recover the files.

There is a procedure to re-attach a Mac to the existing backup once logic boards are replaced, but they assume that there isn't a failure of the backup at the same time.

You should have support from the people who replaced the logic board to help make sure you aren't just missing the steps to re-establish a backup, but if the backup were mine, I'd try backing up to a blank new USB drive and get a good backup now and then troubleshoot the Time Capsule to remedy the error causing the read-only status without risking your only backup. (Since the troubleshooting is to use Disk Utility to repair or erase the Time Capsule and then start over with an initial backup).