Drobo freeze

Just recently purchased my Drobo S about 2 weeks ago and have been extremly happy with it.

However, today it gave me a scare and not sure if this is normal or not. Windows Vista 64 bit system connected via ESata did not see the drive anymore, apparently it went off line sometime in the early AM hours last night as I was using it yesterday evening but backups I had scheduled for 2:00 AM failed.

Odd thing was all lights looked normal and the activity light was not blinking. I first tried disconnecting the ESata cable as this was supposed to be the way I read to put it in standby. Waited about 15 min no change.

Finally pulled the power cord and it did come back up like normal and the system now sees it fine.

Is this normal? Why wouldn’t it go into standby?