Removing removable ATA hard drives

[Jonathan McKeown]

I recently bought a drive caddy for an ATA hard drive. The unit is in two 
parts: a cassette, into which can be fitted a standard ATA hard drive, and a 
carrier permanently fitted into a standard drive bay. The carrier includes a 
power keyswitch for the drive bay.

I installed it, brought the box (running 4.9) back up, and then switched on 
the power to the drive. FreeBSD didn't recognise the drive even after an 
atacontrol reinit of the channel.

I then dropped the box and brought it back up with the keyswitch for the drive 
in the ON position. It now recognises the drive (could this be 
BIOS-related?).

Is it safe to simply switch the power to the drive off using the keyswitch and 
then remove the cassette with the server running but the drive bay powered 
down? Do I need to do anything other than ensure that the drive is unmounted 
at the time?

And having done that, if I replace the drive and then reapply power using the 
keyswitch, would I need to do anything to get FreeBSD to notice the return of 
the device?

I'm reluctant to experiment any more than I have done: the server the drive 
bay has been fitted to is our live fileserver, with 120GB of user data on two 
drives on the other ATA channel.

Jonathan