Andrew Dunn wrote:

Do you think that the controller is dropping out? I know that I have 4
drives on one controller (AOC-USAS-L8i) and 5 drives on the other
controller (SAME make/model). but I think they are sequentially
connected... as in sd[efghi] should be on one device and sd[jklm] should
be on the other... any easy way to verify?

If you are running smartd, cease doing so and do not use the smartctl 
command on drives attached to these controllers - use causes drives to 
be offlined.

It appears the smartctl is broken with LSISAS 1068E based controllers.

See:

https://bugzilla.redhat.com/show_bug.cgi?id=452389

and

http://marc.info/?l=linux-scsi&m=125673590221135&w=2

Regards,

Richard