DROBO told me I need to replace one of the 5 drives in my 5D with a higher capacity drive since memory was getting low. I replaced it with an 8 TB drive. Now the system flashes another yellow light and tells me I am still low on space. DROBO dashboard says I have 16 TB capacity with 9,24 TB used. The notices tell me I have a total of 10.85v TB with only 1.61c free. What is going on? This makes no sense.
Yes, you will need to add/upgrade another drive with a 8TB (or greater) for data replication to balance the distribution in your array. Your new 8TB most likely provisioned memory capacity for expansion but it cannot be fully utilised until it is matched.
Depending on configuration, & specifically if you have dual redundancy & all drives the same size, it’s actually possible to need to replace as many as 3 drives to increase capacity.
Playing with the capacity calculator will doubtless illustrate the issue & possibly guide you.