Drobo S 2nd gen. What are the largest drives that'll (unofficially) work?

Drobo support said that 4tb is the largest officially supported but that it should theoretically work with larger (but untested).

Anyone have success or failure with a larger drive (hopefully a 6tb one)?

No desire to upgrade to a newer drobo as speed is not useful to me-- just need volume.

I have the same issue. I recently replaced an old 750GB with a 4TB on my Drobo S, 2nd Gen (2010) to use on MacPro with Yosemite.
The data reconfigured and Drobo is working - but only shows that I have 4.71TB total usable space when it should says 9.25 with 8.35 TB actual after drive protection.
The drive is there, and working, just not recognized as adding 4TB

I seem to remember them advertising on TWIT that they would accept up to 4TB disks whenever they became available, but that was years ago. I think 2TB’s were just becoming available back then…

4 TB drives work just fine. I have mine maxed out with 4 TB drives. I’m now wondering about 6 and 8 TB drives. Anyone know about these?

The Drobo supports any 3.5" drive, tihs article should be of some help;


I have a Drobo S loaded up with Seagate 8TB drives and it works perfectly. The only thing is that once your volume exceeds 16TB, it will automatically make a second volume to utilize whatever additional space you have.

elai72: So you have a Drobo S with five 6TB drives in it totaling 40Tb over 3 volumes?
Are you able to post a pic of the drobo dash board by any chance?


I was thinking of buying a Seagate 8TB drive, but was waiting for confirmation that it was recognised by a Drobo. Yours is the only response I can find saying so. Can I please just double-check that it recognises the 8TB drive as 8TB, and not as 6TB or something strange due to these drives not officially being supported yet?


40TB total. 32TB usable because 8TB is used for redundancy. It is split in to two 16TB partitions.




Yes 8TB is seen as 8TB. Look at my reply to troy@troden.com. I included links to two images of what it looks like in Drobo dashboard.

this is interesting elai, and it looks promising seeing those green dashboard entries :slight_smile:

i noticed that you are using hfs+ and it seems as though your actual data size is almost at the 16tb of used data. (i think if my estimates are ok, theres still a couple of hundred megs to go before reaching 16tb but i may have done the math wrong :slight_smile: - would be interested to see how things go when your usable value reaches 17tb used.

I still have over 5TB left on the first partition. If/when it gets full, I would expect it to act the same way that any standard full hard drive would react and OS X would just say there isn’t enough room when trying to add more data to it.

hi elai,
just also be careful in case your 2nd volume fills up first, because a drobo must never exceed its own capacity (even if the operating system lets you)

THANKS elai72
The photos are appreciated!

Have 2 WD Red 6TB and 3 WD 4 TB.

Capacity fine, having some I/O and data underrun errors, but issues with stability go back since I received it, can’t saw it’s related.