Replaced 3TB drive with 8TB HD...Still Low Space Warning (Yellow)

Hi guys, just wondering if anyone has any help or answers for me.

I recently replaced the smallest drive in my DroboPro (A 3TB WD) due to my Drobo/Dashboard insisting it was low on ‘free space’. Since all other drives in the unit are 4TB drives I decided to go a larger size and came across a 8TB HD that I thought i’d give a crack.

Long story short: I replaced the 3TB drive with the 8TB drive. DroboPro seemed to recognize it instantly and begin the ‘rebuild process’. After a 40+ hours of the process had successfully completed and DroboPro recognized the 8TB drive but ‘still gives me the same warning’

WTF Right?

I had only 2x 16TB Volumes on it and decided I’d create another 16TB partition/volume and see if that did anything. - Nope!

So the situation I have now is:

DroboPro with 8TB-4TB-4TB-4TB-4TB-4TB -4TB-4TB inserted
3 x 16 Volumes (Single HD Redundancy Only)

8TB HD still orange light - (Capacity warnings still being received).

Anyone shed any light on this, or if they have tried 8TB drives in theirs?

Two things:

1). In your setup if you replaced your 3tb drive with an 8tb drive, it would give you 1tb more space than you had before (try it in the drobo capacity calculator)

  1. is it a seagate 8tb archive drive? If so take it out - do not use those drives in any drobo (yet); they are not supported and will cause problems

Drobos aren’t yet aware of shingled drive (SMR) and will need a firmware update before they can be used (which may not may not happen since shingled drives tends to be a poor choice for RAID arrays)

Thank you for you’re help Docchris. Really appreciate it.

I would have thought inserting an 8TB drive would give me more free space then 1TB, I was under the impression I was not limited to the amount of volumes I could have with the DroboPro as long as they were all (16TBmax) so inserting larger size HD’s would give me that benefit.

Using the drobo calculator isn’t available for DroboPro’s anymore.

So what your saying in other words is the DroboPro will never support more space then 32TB (4x4x4x4x4x4x4x4 drives). So even using a 6TB drive would not let me utilize more then 1TB space correct?

I guess the main question here is, can we DroboPro users ever use larger drives or not…and the short answer is…“No” (throw our your DroboPro’s and get a new model that can support 64TB)

Things like “Supports 32TB and beyond” or “Room for expansion” “Future proof” were just sales gimmick from data-robtics and we’re left high and dry as customers.

A Drobo firmware update for SMR drives will never come for my product regardless because it is considered an obsolete or as they put it a ‘legacy’ product, so i’m well and truly f#cked now.


I should have explained myself clearer

its in YOUR SPECIFIC SETUP that the 8th Drive is only giving you an additional 1 tb of space (because it is the only 8tb drive you have in there)

Space in your Drobopro (assuming that you are using single disk redundancy) is:

The total of all of your disks… minus the largest disk


3+4+4+4+4+4+4+4 = 31TB . minus 4TB (doenst matter which one) = 27Tb available for storage


8+4+4+4+4+4+4+4 = 36TB minus your largest disk (8TB) = 28TB available for storage

so you have gained 1 extra TB of usable space

in terms of concept… its using the “bottom” 4TB of your 8tb disk… but because you only have a single 8TB… it has nowhere to protect/mirror the “top” 4tb half of the 8TB disk, so it cant protect that, so it doenst use it at the moment

you should be able to see this unused 4tb slab of your disk as “reserved for expansion”.

if you add another 6 or 8 tb disk now… you will get all of the additional space you would expect

as far as i know there is no reason you could not successfully use eight 8 tb disks for 64tb of total capacity (56TB usable)

still… Dont use the seagate 8tb archive drives, they use SMR which drobo’s dont currently support