Best Practice for Time Machine on old Drobos?

I recently bought a used Drobo (Gen. 2) to replace my old Gen 2 Drobo that died after the power supply shorted and burned the circuits in the enclosure. While I would have liked to upgrade to a newer model, I don’t have the funds currently, so I had to settle for another Gen 2 to be able to keep the data on my disk pack. Now, the sudden demise of the old Drobo left the drives a bit unreliable, so I have backed up all the data and reformatted the entire Drobo disk pack.

Now for the question: What are the current thoughts on using a Drobo Gen. 2 as a Time Machine backup? When I bought my original Drobo, I formatted it to use 4 TB volumes, and chose one as my Time Machine drive. However, later i read tips on using Sparse Images and the Time Tamer app. At that time I had no interest in switching my approach, but now that I’m beginning fresh, I’d like to examine the alternatives. I really don’t need 4 TB of Time Machine backups (2 TB will do), and as my old TM backup grew I felt that it became incredibly sluggish and perhaps even affected the performance of the Drobo in general.

The problem is that the Gen 2 is now outdated and I’m having trouble finding any articles on this in the KB. Some advice would be great! Do I let Drobo Dashboard partition my disk pack into 2 TB volumes, should I create a .sparseimage in some way or use Disk Utility to partition a 2 TB drive from a 16 TB Drobo volume? Or something else I haven’t thought of?

I’m using Yosemite on an iMac (late 2012) with a 1 TB Fusion drive, and my Drobo has 4 x 2 TB drives.

I notice you got no responses.

I, too, am curious how to best setup a Drobo Gen 2 to work with Time Machine on Yosemite on MacBook Pro from Late 2011.

Anyone have advice on this? I’m not seeing a lot of helpful info in the Knowledge Base Articles.

I have a Drobo S and just put in new bigger drives. They’re all green, but Dashboard now has two partitions, and it says that one needs to be formatted. I’m not getting the full size of my drives (5 x 5TB, showing as 18TB). Not sure what to do now. I’m assuming reformat, but what’s the best approach now for that? Use Disk Utility?

I currently have two partitions, one I keep empty and the other is my Time Machine target. I set this up years ago and can’t find the directions I followed (it seems Drobo Knowledgebase has wiped all relevant articles, including up shown as updated yesterday that is totally blank). I’m past the support period so I’d appreciate any help. Thanks.


hi, for the non-timemachine aspects here is some info that might help…

if you have a drobo-s it will have at least SDR (single drive redundancy) or DDR (dual drive redundancy)
this basically means that at least 1 drive (or 2) can fail while keeping things running.

sdr takes up about the same overall size as your largest drive
(and ddr, the same as 2 largest drives)

so if you have 5x5tb = 25TB raw
then with sdr you actually have 20tb capacity
of which, the filesystem (mac or windows etc) usually takes up some space.

so if we take that 20tb and x by 0.9 = 18tb available.

this sounds like you are running in SDR mode (which your dashboard will probably show you in one of the screens), and that it seems normal. :slight_smile:

if you upgraded drives, then as your capacity increases, they may well get more volumes.
this also depends on which size you selected as the max volume size, when you first set up the drobo.

if dashboard has told you that it made another volume/partition and if dashboard is asking you for a drive letter or is offering to format it, then it sounds ok as this is what happened for me on windows, but please find another thread here with more information about it which may help:


(btw if you can post back those links that you used to use, that would be useful for reference for the website owner)

Thanks, Paul. That’s very helpful on the regular Drobo stuff. It shows two partitions, each 16TB which seems odd to me, but everything else fits with what you wrote.

Still trying to figure the TimeMachine aspect. Anyone?

Here is the blank article in Knowledge Base: http://myproducts.drobo.com/article/AA-01461 How-To: Using Time Machine with Direct-Attached (DAS) Drobos
Article ID AA-01461 | Date Updated: 09/11/2015 09:41 PM



thanks stephen,

for the 16tb volumes that you have, thats sounds ok, as thats how they present them selves to the operating system to allow for future expasion.

one thing to remember though, is that dashboard (and drobo blues lights to some degree) will show you your true remaining usable space which is available, so always try to remember to look there so that you do not over fill your drobo.

another user john has mentioned a website called pondini before, which has information about time machine, though im not sure if it’s TM in general, or related to drobo and TM, but hopefully you can find out more info soon :slight_smile:

It’s general advice about Time Machine, how it works and what to do when it doesn’t, and it’s here. I didn’t respond earlier because the only Drobo I have is a 5N, which is a network attached device which can only use the sparse bundle approach. Have a look through the other threads in this section and search for Time Machine in the other sections relevant to your device. I seem to remember reading that you can use either approach so use whatever works for you. The “normal” mode for DAS devices would be to dedicate a whole partition to Time Machine backups - people often dedicate a whole USB or Firewire connected hard disk to the purpose (even Thunderbolt is a possibility but that would be something of a waste). So decide how much storage space you want to dedicate to Time Machine and do that. You say you have 1 TB on your Mac and a number of 2 TB volumes on your Drobo so dedicating one of them to Time Machine would seem very reasonable to me. I remember reading on one thread that someone uses a directly attached Drobo connected to a Mac Mini and sharing out one of the volumes via AFP for other Macs to use as Time Machine backup space, which imposes the sparse bundle approach since it’s a network share. Sparse bundles work but they are an extra level of complication with more potential for failure or corruption than simply dedicating a drive or partition to the task.

many thanks john,

btw an older admin called jennifer made a post about some of the older models which might have good info too (slightly older post but maybe useful)

(edit - fairly older post) :slight_smile:

Thank you both! I’ll check those out.