I’m upgrading the storage in my 1st-gen Drobo S (Firmware 2.1.3, Drobo Dashboard 2.2.3) from five identical 3-Tb drives to five identical 4-Tb drives. Before I did this, storage was at 86% (dual drive redundancy according to DD but these days who knows w/o a log file?). The Drobo spontaneously turned on a yellow light next to the top drive in the stack. No problem; I made sure that was the first drive I changed out for a bigger one. When the relayout finished for the first replacement drive, imagine my surprise when I found that there was still a yellow light next to the top drive in the stack, even though it was now the largest drive in the stack: a 4-Tb drive.
What the heck?
This is the last drive that should be getting a yellow light now! ANY one of the other four drives (i.e. the 3-Tb drives) would be a better candidate! If the Drobo is supposed to help the naive operate a sophisticated RAID array, this is not the sort of thing it should be doing.