I hot removed a malfunctioning drive in my FreeNAS unit recently. The problem is its replacement would not show up in available drives. Camcontrol devlist wouldn’t reveal the device, even after camcontrol rescan all.

I found from this site that another command exists – camcontrol reset. I found out which bus to reset (instead of resetting all of them) by looking at logs and noticing the scbus number. Once obtained, I ran the following commands (the last number refers to the bus my drive was on)

sudo camcontrol reset 10
sudo camcontrol rescan 10

That did the trick! The drive was suddenly visible by the FreeNAS system once more.