kern/152720: Weird Hard Disk clicking noise on system shutdown

[brucec at FreeBSD.org]

Synopsis: Weird Hard Disk clicking noise on system shutdown

State-Changed-From-To: open->closed
State-Changed-By: brucec
State-Changed-When: Tue Nov 30 23:20:06 UTC 2010
State-Changed-Why: 
The clicking sound is an Emegency Unload being done as the drive loses 
power. This is fixed in stable/7 and stable/8 by spinning the disks down 
during shutdown if the cam subsystem is being used (i.e. ATA_CAM or ahci(4)). 
It's unlikely that the ata(4) driver will get the same fix 
since it's being deprecated in favour of 
ATA_CAM and ahci(4), and it has issues with power management.


Responsible-Changed-From-To: freebsd-bugs->brucec 
Responsible-Changed-By: brucec
Responsible-Changed-When: Tue Nov 30 23:20:06 UTC 2010
Responsible-Changed-Why: 
Track.

http://www.freebsd.org/cgi/query-pr.cgi?pr=152720