6TB disks compatibility

I have a Drobo 5N with 5x 4TB HGST disks. It works fine.
But I need to replace these disks whith larger ones (I have a yellow alert)
So I ask if Drobo 5N supports 6TB disks?

what price are you getting these 6TB disks for?

From what i have seen you’d probably be better off actually buy a second drobo and filling it with 4Tb disks!

Don’t forget that adding a single 6TB disk will do nothing to help you, you need to have at least TWO 6TB disks to gain any additional space.

Other than that i do not believe there is any reason 6TB disks would not be supported

I went to replace all disks. The cost is 300$ per disk (seagate)
I prefer to have only one drobo because I travel a lot.
And I ask this question because I don’t see the 6TO disk in the “Capacity calculator” page.


this thread is what you are after.

basically they should work, but they havent completed testing yet, so i guess it depends how recent your backups are as to whether you take the risk

Ive just got 5x6T WD RED disks in a new 5N (my third Drobo device) and its working fine with the Drobo Dashboard displaying 21.76TB total (i.e. after the redundant space and overhead etc).

HOWEVER it also shows 5.76TB (26%) of the total (21.76TB) space as Unallocated. I’m not sure if this is some sort of 16Tb address restriction?

I don’t know whether its a firmware/ Drobo OS or simply a dashboard problem? it would be great to have the 6TB working correctly.

I recall reading somewhere that any space after 16TB needs to be configured as a second volume. Does your Drobo Dashboard allude to this in any way?

This is exactly what I’m wondering. I just bought a 5N to replace my FS. I’m going to start from scratch and was planning on starting to buy 6TB drives but it will go above the 16TB limit of the 5N.

According to what I’m reading only space up to 16TB will be available. Is there a way to solve that problem or for now I should stick with 4TB drives to not go above the 16TB limit?

Also will it be possible in the future to go above this limit without reformating? Will be just impossible to format with 16TB of data on the drobo…

This is only true for direct attached devices (and not 4-/5-bay NAS) and is done automatically by the Drobo.

Currently you can up to 16GB usable drive space (excl. redundancy). So 5*6TB with dual drive redundancy will give you (5-2)*6TB = 18TB which implies that you loose 2TB with this setup because of the 16TB limit.

With single drive redundancy it’s worse: (5-1)*6TB = 24TB. In this case you could go with only 4 drives which will make no difference capacity wise.

In the future if an update is shipped to overcome the 16TB limitation, would it need to be reformatted entirely or it could be possible to just change it for another capacity?

Also can you switch from a single-drive redundancy to 2 double-drive redundancy (and vice-versa) or once it is setup you can go back unless you format?

this is absolutely NOT only true for DAS devices.

The DroboPro FS - a NAS drobo, configures itself to have TWO 16TB volumes to “allow for future expansion”.

if the Drobo FS /5N only has a single 16TB volume, then we would need to confirm if it would automatically create a second 16TB volume or not - and to my knowledge no one has actually tested this.

if it can automatically create additional volumes as / when needed, then why would the FS create two to start with.

and then you also need a mechanisms to choose which shares go on which volumes, which you do get with the 8 bay NAS drobo, but i dont know if you can do that with the 5 bay one.

You can switch back-and-forth between them with no issues, providing you have sufficient free space available.

So it seems this function is also available for the 5N, according to a discussion I just had with drobo people on twitter: https://twitter.com/drobo/status/552912819016839168

Basically if you have more than 16TB a second volume is created.

Anyone would have more details on that?

Okay. I didn’t know details about the Drobo FS. I thought it would be the same as for the 5N. There was a post somewhere in this forum about a user with >16TB drives that ended up with a few TB unused drive space with no option for a second volume (Drobo 5N).

Currently this is not true for the released Drobo 5N firmware.
A local dealer (that sells the Drobo 5N with 30TB drive capacity) got the official statement that the Drobo 5N supports up to 20TB drive capacity. Since it does officially support 4TB drives this sounds plausible: 4TB * (5 - 1 redundancy).

It could be that Drobo Inc. is internally already testing a future firmware revision that behaves as they stated in the twitter message. Or they mixed up 5N / 5D / FS… who knows. :slight_smile:


according to that, at the moment 16Tb is the limit for a Drobo 5N