replaced da devices not being detected

[Graham Allan]

Running a FreeBSD 9.1 server with four attached Supermicro SAS JBODs, 45 
drives in each. Sometimes when we replace a drive due to failure, the 
new drive isn't detected. At that point we can swap the drive in and out 
or between vacant slots with nothing appearing in dmesg or other logs. 
But we know the drive is working because it is detected by the chassis 
if queried with sg3utils. No effect from "camcontrol rescan" etc, 
either. Rebooting the server does result in the drive being detected but 
obviously this isn't a desirable way to fix it.

It does seem to me like we get to replace some number of drives without 
incident, then after some point no new da devices are detected.

Just wondering if anyone has seen this, or if there are any sysctls 
which might affect it or other ways to tickle the system into behaving 
as expected.

Thanks for any advice,

Graham
-- 
-------------------------------------------------------------------------
Graham Allan
School of Physics and Astronomy - University of Minnesota
-------------------------------------------------------------------------