Need Help Ensuring Drobo/ Time Machine Is Properly Configured.

I recently bought a traditional, 2nd gen. 4 bay Drobo. I have put in two 2tb drives and 2 1tb drives. Before this I only had a 1tb external drive and a 2tb external drive attached to my Mac. All three devices are still connected. I am fairly certain I have set my Drobo properly to back up my 1tb internal drive via Time Machine; the rest is used for additional storage. I’ve included a snapshot to try to give people an idea of how i have things set up. I installed Time Tamer, because I heard Time Machine will try to use all available storage on the Drobo. With this, it limits the backup of Time Machine to 1.83tb.
My questions:

  • Is the Drobo configured properly, to back up Time Machine?
  • If so, can I store or sell my other HDDs (after wiping them, of course.)? All of the RAID, BeyondRAID, data redundancy stuff is still a bit new and confusing to me.
  • Is Time Tamer configured properly, and if so, is 1.83tb too much For a 1tb drive?

Is anyone able to help me with ANY of the questions asked? Any help is appreciated.

I never used Time Tamer, but the usual way to “contain” Time Machine is to dedicate to it a limited size partition; in the case of the Drobo, it should be the first one (the last one is of a “virtual” size only limited by the initial Drobo formatting, called thin provisionning).
Anyway, be advised that Time Machine performance on a Drobo is usually very poor, due to the internal fragmentation generated by the Beyond Raid algorithm of the Drobo. Drobo works best with large files rarely updated.

Time Machine assumes it can use 100% of the space that you point it to, so creating a fixed size partition on the Drobo (or a sparseimage like TimeTamer creates) is required, or time Machine will think it can use all the space on your Drobo, and will run into problems as it approaches the physical limit of your storage where the Drobo slows to a crawl.

(By the way, from your screenshot it looks like you didn’t format to 16TB, and you only did 8TB. There’s no reason not to use 16TB on a Mac, there’s no performance penalty. If it’s not too late I’d reformat now before you have much data on there…)

As for sizing, if you want to be sure you can back up every byte of your drive, you need at least the same size as the drive you are backing up, there’s no compression in Time Machine that I know of. After that any extra space you give it will be used to store previous versions of files, and file you have deleted. How much of that you want to do is up to you. The size you chose seems OK to me.

I took a look at the setup you show. It shows Time Machine pointed at a volume called Drobo that has 7.24TB free out of 8.8TB. This is I think wrong. Time Tamer doesn’t “install” anything. All it does is make a thing called a sparseimage. You then have to put that file on your Drobo, mount it (by double-clicking it), then point Time Machine at that virtual volume, not at your Drobo.

Thanks for the responses guys. I did not set it to 16TB, so I’m in the process of transferring the data back to another external hard drive, wiping out the Drobo, and starting again. Here’s what I’m planning. Please tell me if this sounds like a good course of action.

  1. I’m currently transferring the data from the Drobo back to a WD 2TB external I still have.

  2. After this, I will do a pin reset of the Drobo, wiping everything out.

  3. When formatting the Drobo, set it to 16TB, and set up Time Tamer.

(Spiney, I’m a little confused. So are you saying setting up a sparse image with Time Tamer for Time Machine will not limit the amount of space the Drobo will allow Time Machine to acquire? What is the specific course of action I need to take to have Time Machine backup to Drobo, without it trying to take over the entire drive?)

  1. Transfer the data back.

Another question - I’ll be honest, I don’t have a great understanding on how the technology of the Drobo works. I’ve replaced a few 1TB drives in the Drobo with 2TB drives. Do those 1TB drives have anything on them, or am I able to put them up on eBay without worrying about any personal data still being on them?
Also, once I have Drobo configured properly, is there any need for any other external drives? I have a 1TB and a 2TB external drive, and would like to wipe those and sell those as well, if not needed.


Mount the sparse image that TimeTamer created (double-clicking it should do the trick), then point Time Machine at the sparse image to back up. That will do the limiting. It should mount itself automatically if it isn’t mounted at the time that Time Machine runs. If you just point it at the Drobo volume then it will fill the Drobo…

They have stuff on them, but it’s mangled due to the way Drobo works. It’s not encrypted though, so if people try hard they would be able to find snippets of your stuff. I’d clean them first. Put them in a USB case and run erase them from Disk Utility using one of the secure options. You might want to hold onto at least some of them though (see below…).

Remember: Drobo is redundancy, not backup. It protects against drive failure, not against accidental deletion. You do have Time Machine for that as long as your Drobo is accessible. I’d rsync (or some other copy mechanism) your important documents from the Drobo to another drive at regular intervals, so I’d keep at least some of the spare drives to backup the Drobo.

I haven’t created any specific partition for my time machine backups.
Currently, 1 year worth of backups for 2 different macs at home take less than 200gb and since I have about 2TB available I won’t worry about TM assuming it actually use 16TB of space.