Connected Data, creator of the Drobo line of Network Attached Storage (NAS) devices has released a software update for its newer devices that will be interesting to Time Machine users. The company has announced updated Drobo software for the Drobo 5D and Drobo mini that allow them to be used for Time Machine backups.
The update comes in the form of new firmware (v.3.1.1) and a new version of the Drobo dashboard software (v.2.6.2) that allows certain Drobo devices to be seen by Apple's Time Machine software. The new feature is limited to the company's Drobo Direct Attached models, which include the Drobo mini and Drobo 5D.
To make a Drobo Time Machine capable you need to create a dedicated, fixed capacity volume for Time Machine within Drobo Dashboard. This can be done without disturbing your existing data.
Within Drobo Dashboard just click on Volumes (in the left navigation) then on the button for "Enable Backup/Time Machine volume" (above). The next screen asks what size you'd like the Time Machine volume (in GB) to be and I entered 4096 GB, or 4TB. Connected Data recommends that you allocate two times the amount of space you need to backup between all of your devices. So if you're backing up two Macs with 1TB drives, you should create a 4TB Drobo volume for Time Machine.
No need for complicated partitioning of the main volume in order to reserve space for backups
The size of this volume can be set to a fixed capacity for Time Machine to use
The ability to set capacity limits eliminates the need to create sparse bundle files
Time Machine Backup Volume wizard auto detects the best size based on the internal disk capacity
Encryption such as OS X FileVault is supported on a Drobo Time Machine Backup Volume
Can delete and recreate the Backup Volume with a different size without affecting the data volume.
Overall the process required a couple reboots of my Drobo 5D, once to update the firmware and another to partition the disks, but was relatively painless. I've now got a dedicated 4TB Time Machine partition in what was otherwise unused space on a 20TB Drobo.