Stop using a SATA drive

[Chris Stankevitz]

How can I tell FreeBSD to stop using a SATA drive?  I'd like to pull
it from my machine (while the machine is running) but I'd like to be
confident that nothing is using it.

I imagine I would feel confident that nothing is using it if the drive
disappeared from /dev and it stopped spinning.  "camcontrol stop" did
not accomplish this (that was a WAG -- camcontrol man page says that
'stop' only sends the 0x1B command whatever that means).

Please let me know if you can imagine a better place for me to ask
this question or learn more about the process.

Chris