The right way to remove disk drive

[Miroslav Lachman]

Hi all,

what is the right way to remove disk drive from running system without 
reboot?

I have Sun Fire X2100 with 2 identical drives in gmirror. One drive is 
failing, so I want to replace this drive by another. Drive is no more 
used by gmirror (gmirror status shows DEGRADED and running on one drive 
only), atacontrol lists the drive attached to channel ata3, so I run 
command `atacontrol detach ata3`. As stated in manpage "Devices on the 
channel are removed from the kernel". Everything goes fine, system is 
running.... but if I pull out the drive tray, system hangs and must be 
power cycled.

I had some worse problem with disk drive few month ago and if drive 
disappeared completely from system (not visible by gmirror nor 
atacontrol), I pulled out failed drive and system was running fine. Then 
I replace the drive, system detected the new drive successfuly, then I 
start gmirror synchronization... all in few minutes without reboot.

So what is wrong with manual removing drive?

System is 6.2 RELEASE with GENERIC kernel, gmirror loaded from 
loader.conf, but previous disk replacement was in time of 6.1 RELEASE.
Is there any known 'new' problems in 6.2?

Miroslav Lachman