From our KB Article : Why do I get a “Disk Removal Error” when Drobo or DroboPro awakens from sleep (Mac)?
This issue appears after the following sequence:
You wake up your Mac.
Drobo or DroboPro sounds like it is waking up. Then all drive lights turn red and all of the blue lights come on.
Drobo or DroboPro then reboots itself.
The Mac’s “device removal” warning appears after reboot.
The Data Robotics engineering team has looked at this problem closely. The team concluded that the most likely cause is a bad drive that is taking too long to spin up. Whenever drive(s) don’t spin up properly or promptly, Drobo and DroboPro perform a controlled reboot.
Try these tests to identify a drive or bay that is misbehaving:
Safely shut down Drobo or safely shut down DroboPro.
Move drives to different bays. Ensure each drive is firmly seated.
Reboot Drobo by first connecting the data cable and then connecting the power cord. Reboot DroboPro by flipping the power toggle on the back of DroboPro.
Retry your sleep test to see if the pattern has stopped.
You can also try this same sequence but remove one drive at a time from your drive pack before rebooting and retrying your sleep test. If a drive is bad, the misbehavior should stop when the bad drive is removed.