Using Drobo and Drobo Share with Time Machine
Recently I have bought a Drobo and a Drobo Share. One of the reasons for this purchase was to be able to easily expand disk storage capabilities and have a central location to store Time Machine backups for both my Macs.
When I had installed my Drobo and Drobo Share I soon noticed that by default Time Machine does not allow NAS systems to be used as Time Machine backup disks. After a bit of research on the net I found that it is possible but it needs a little bit of work.
This blog post details the step I performed to setup Time Machine for my Macs
1) Setup your Drobo and Drobo Share and make sure everything is in working order and you have enough free space available to store Time Machine Backup data onto your Drobo.
2) For every Mac to be backup-ed using time machine create a sparse bundle image. You can create this disk image by using Disk Utility

Normally a volume size of twice the actual size of the HDD installed in your Mac should be adequate to store multiple versions of your files into the Time Machine backup. If you have enough storage in your Drobo you can make the disk image larger. After the sparse bundle has been created make sure to eject the disk image.
2) Copy the disk image to the root folder of your Drobo
3) Open a Terminal session and execute the following command on every Mac to be backup-ed by Time Machine
defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1
4) Start Time Machine and select you Drobo as Time Machine Disk. For for Time Machine to start, moste likely it will fail or just stop the prepare action as soon as it starts. If you now look at the contect of the root folder of your Drobo you will notice that one additional file is created. This file is named something like this
Atum_001debec863e.temp.sparsebundle
Atum in my case is the name of my MacBook Pro, and 001debec863e is an identifier used by Time Machine to identify the machine.
Use the first part of the name (Atum_001debec863e) to rename the temp.sparsebundle into its proper name for Time Macine. In my case that would be
Atum_001debec863e.sparsebundle.
4) As soon as Time Machine is done working you can click on the ‘Change Disk…’-button in the Time Machine preference pane and select None from the list.

5) You can now delete the xxx.temp.sparsebundle from your Drobo.
6) Now again you select your Drobo as a Time Machine Disk. This time there should be no errors and Time Machine will start backing up your Mac.

I have used to following resources from macosxhints.com while figuring out how to setup Time Machine in combination with my Drobo and Drobo Share
[1] – Create a Time Machine size limit for networked disks
[2] – Set up Time Machine on a NAS in three easy steps

Do these instructions work for a Mac-formatted Drobo drive or should they work for NTFS as well? I got stuck at the stage where Time Machine should be seeing the DroboShare/Drobo – no go.
You will need a Mac-formatted (or FAT32) drive for Time machine.
I just discovered your blog as a result of purchasing a Drobo with Droboshare.
In step 2) you instruct the reader to Copy the disk image to the root folder of your Drobo. Where do I find the root folder of the Drobo?
The root folder is the top level folder of the Drobo (or any disk). Copying the file to the root folder is the same as dropping (moving) the file onto the Drobo icon on your desktop
Hello,
Just wanted to tell everyone that there’s an additional step you might want to take to get the name of your disk image correct. Go to http://www.readynas.com/?p=253 and follow the instruction at (2) to get the correct Ethernet address. In terminal, run:
fconfig en0 | grep ether
Copy the the resulting address to a text editor, strip out the colons and then place the resultant text in the filename of your Time Machine disk image, ie:
MY_MACS_NAME_0016cbaf91d7.sparsebundle
This should work running Drobo over DroboShare using a MacBook Pro running 10.6.2.
I’d also like to point out that you will need to manually mount your Drobo in finder if you’re using DroboShare. See http://support.datarobotics.com/app/answers/detail/a_id/73/p/5/r_id/100004. This problem may go away in later releases of the DroboShare firmware.
I used Automator to create a simple script to connect to my Drobo over the network; in addition, you can also go into Finder – Go – Connect to Server and do it from there.
Good luck!
Eric
One more thing I just found out about:
You’re better off connecting your Drobo using Firewire 800 to do your first Time Machine backup. Mine took over an hour since I had over 100 gigs of crap to back up. Once Time Machine finished doing its thing I took the Drobo and re-connected it over the network. Setting Time Machine to then use the Drobo over the network, my next backup took less than a minute.
Hope this helps.
P.S. I keep a robot blog over at:
http://mobilerobots.wordpress.com/
Eric
Hi
I have multiple Macs and one Drobo Pro – and I would like to follow your guide to use the Drobo Pro for TimeMachine-backup of all my Macs…..
But – I get to step 4 and I don’t get any new file. My TimeMachine dashboard reacts (I think) as you’re talking about, denying to finish the backup, but I’m not given any new file to use for renaming afterwards.
Any help would be highly appreciated :)
Hi,
I have stopped using my Drobo for doing Time Machine backups. Over time my sparse bundle got corrupted and I had to start all over. This happened a couple of times making me rethink this strategy. I have since moved to BackBlaze which offers an online backup service which fulfills my backup needs (besides the ccc-backups I also create regularly).
Regards,
Frank