Thank you for your reply, Bhiga.
I checked out the boot sequence and for hard drives that was (1) SSD C Drive, (2) single non-RAID drive, (3) Drobo, (4) “Bootable addin-cards” so I don’t think that was a problem. I seem to have removed the Drobo from that but it still took 6 minutes to boot up.
I looked for eSata controllers in Device Manager but couldn’t see anything that seemed to fit. The manual says the eSata controller is built into the “JMicron JMB362” chip, so maybe there’s no control for it there.
While I was doing this, the Drobo also dropped off after bootup.
But you started me thinking on what I could check on the PC. I haven’t had it for long and I got someone more knowledgeable than me to build the components so I just presumed it was all set up and everything should just work. So I fired up the motherboard utility disk, downloaded all the chipset drivers and enabled a fast boot option. Now it boots up in 50 seconds with the Drobo connected by eSata and the Drobo has stayed on through numerous rebooting cycles. Probably all I needed to do was download the drivers. I’ll find out for sure in the next few days.