changed 1TB drive to 2TB drive, still wants more

Hi! I got following problem. Drobo said I have to change a 1TB to a bigger drive (red light constantly), so I bought a 2TB and replaced it. Now it still says I have to swap the 2TB Drive to a bigger one! (it recognized it, cause in dashboard it shows the 2TB disk.

I didnt do any backups after the switch, so not more data got on drobo. What makes me totally wonder is why didnt ask it to swap one of the older 1TB… I mean I have put 1TB on top, and still the message of not enough space…

updated all firmware, driver. Put on stand by etc… no luck…


If you have 4 drives that are all the same size, you will need to upsize 2 drives in order to increase your capacity.

Please see our capacity calculator:

He is saying it’s asking him to replace the new 2tb one, he (and I ) would have expected it to ask him to replace one of his “old” 1tb ones

Then reboot the drobo.

Standby from standby, unplug usb/fw then power. Wait 30 seconds. Then plug in usb/fw and then power.

Hi I did exactly the same like you said. It recognized it, made a security check (sorry I got it in german - so I dont know the exact word for it), but it is the same result then before. I even swapped the 2TB with another 1TB, cause I thought it might be the slot, but it showed the same in the new slot. Here is a screenshot of it:

Put your drobo into standby via dashboard.
Unplug usb/fw then power.
Swap one of the 1TB drives with the 2TB drive.
Plug in usb/fw then power.

Do you get the same message?

Thats what I did. It is the same, just in the new slot.[hr]
Maybe the drive is not compatible? Its a samsung 2TB.

Should be compatible.

I would recommend opening a support case.

I will try to get another 2TB disk, then I’ll see…

it looks like it just doenst have enough working space to do the the rebuild (thats screenshot has it very full)

is it possible to move 100gb off drobo onto another drive somewhere (make sure you have a backup of this since when its not on drobo its not protected).

once that is done leave it and see if it starts to rebuild.
if not then try the restart as detailed by jennifer.

i think that will kick it into rebuilding.

I deleted 300gb… made standby, waited a minute…cables back together, it started to make this security check… but then the same… it says change the 2TB disk…

Finally I formated the drive and it seems to see ll drives.

I just have a question formating. I got now 3 1tb and 1 x 2tb = 5tb

When I format I can decide 4 or 8. What should I choose? Its always says 2.7tb usable…

that is thin provisioning

it is up to you - on windows larger volumes can take longer to start up.

volumes of more than 2tb are only compatible with newer OSs

personally i’d pick a larger one as it will save you from having to create a second volume when you add disk space

(if you picked a 4tb volume - then when you get more than 4.0 tb available as actual capacity it will make a second 4tb volume - if you picked 8tb formatting, then you will be able to add a lot more disk space before it creates a second volume.)

some people like having multiple volumes, others dont

Okay, I have snow leopard server. So I think I will not add more than 2TB in each slot (I dont trust more), so the highest will be 8tb, right? So I should format it at 8tb?

Its says 2.7tb, cause I only have 5tb in the moment?

There’s no penalty on Mac for going with the 16TB volume size. At some point you WILL trust >2TB drives and you’ll wish you had done 16TB instead of 8TB when you are trying to find some place to put 8TB of data temporarily while you reformat.

(I made the mistake of formatting at 4TB on mine when I thought there was a downside, and it too me over two weeks to copy all the data off the Drobo to a NAS temporarily, and then back again after reformatting…)