Does anyone know, what is the largest capacity of drive i can add to my drobo?
Currently i have 14tb drives.
Can i add 18tb or even 20tb drives?
Officially, Drobo has tested drives up to 14TB large:
https://myproducts.drobo.com/retrieve/s3/knowledge/AA/AA-01124.html
However, the Capacity Calculator lets you estimate how much capacity you would have on your 8D using drives up to 18TB big, which seems to indicate that 18TB drives are supported for your device.
Finally, the last firmware for the 8D shows that there wer fixes made for drives over 16TB:
I am successfully using a 20TB drive in my 5N2, which released before your 8D.
I think you should be fine using 18TB or 20TB drives.
Good luck!
Regards,
Dom