Last week the Drobo was getting full. (2TB, 2TB, 1.5TB, 1.5TB) so I replaced the 1.5TB with a 3TB. No problem after about 5 days the data was rebuilt. (2TB, 2TB, 1.5TB 3TB.)

Today the the other 1.5TB light is yellow. I pull the drive and replace it with a 3TB. Now all the lights are red. Not a good sign to me. So I replace the old 1.5TB back into its slot and got 4 red lights again.

I tried again to swap the 1.5TB and new 3TB drives and still 4 red lights.

So I replaced the new 3TB with the old 1.5TB drive and have 4 red lights. The dashboard show I need to replace 2 drives (the 1.5TB and an older 2TB) I don’t think that seems right to me. My understanding is that you should only replace one drive at a time.

The drive is offline and I can not see it on my desktop.

Any suggestions?


i’m in a similar situation, did you get anywhere with this problem?

hi, when you pulled the other drive, are you sure it was a solid yellow, or was it possibly flashing yellow/green?

if it was solid yellow, it should mean its suggesting a larger drive is added here, but just in case it was yellow blinking, it would mean dont remove the drive.

as its been a few days since your post it might be worth waiting a few more but if you cant, and if your drobo is not blinking lights and making drive chatter etc, you could try powering off the computer, and the drobo, and unplugging the drobo computer cable, and powering the drobo back up to see what it does?
and to then try booting up your computer again to see if dashboard/computer can see it?[hr]
also have a look here in case helps regarding firmware question:

I also had problems when I unhooked by Drobo 2nd Gen from my old Mac to the new MAC I just got this Christmas. It is a fully loaded 5K, 27inch.

I tired to reformat my Drobo, but I received a message that made no sense, so I decided to just hook it up and do a back up.

It took 24 hours but finally all 4 lights were green for a minute.

The top bay turned yellow, so I took out the 1tb drive and replaced it with a 3tb. I now have 3tb, 1tb, 2tb & 2tb

The alternate blinking of yellow & green is taking place, but it has been 24 hours. The last time I replaced a drive it took less than 10 hours.

Is it normal to take this long??? I think you said 5 days???

Should I just sit back and wait, or is there something else to do??

Thanks for any help or opinions…