I have a Gen 2 with 4x 2TB drives. Everything has been running smoothly.
I have 1.4.2 Fireware installed and running it on a Mac Mini with the latest Yosemite.
I had no warning lights but I am adding 2 3TB drives to increase capacity. I removed the drive in the 4th bay and all the bay lights turned red. The Drobo unmounted. I got a warning from the OS saying the drive had been ejected incorrectly. Drobo dashboard no longer saw the drive. I inserted the new 3TB drive and waited a minute. Everything stayed blinking red. I removed the new drive and put the old drive back in. After a few moments all 4 bays started flashing amber. Now it is in data protection mode even though I put the old drive back in.
I’m guessing I have to wait several days to try to replace the drive again.
Anyone know why the Drobo unmounted when I pulled the drive out?
im not 100% sure, though do you think it is possible that another drive might have been slightly loosened by the action of removing that 4th bottom bay drive (and making an intermittent connection)? if so, it could have caused the drobo to essentially only have 2 drives present (for the disk pack) rather than 3 drives for a moment.
either way, it is certainly good that you are waiting until the current rebuild completes successfully again. one thing you could do though when its completed, could be as follows:
to use dashboard to safely shutdown the drobo, and then to unplug all power and connection cables from it.
to reboot the mac
to eject all of your drives from the (unpowered and disconnected) drobo, and to gently but firmly enough re-seat them back into their place, just to make sure all is making a good connection.
and then to power up the drobo as you normally would, and to verify that all is green and all slots are recognised as per normal, and with computer access again.
and then to try removing the bottom drive again (and to wait at least a few minutes for the unit and dashboard to recognise that the drive is missing… and to hopefully not enounter an all bay slots blinking red this time around?)