For example:

# bioctl arc0
Volume  Status               Size Device 
 arc0 0 Online      1999999336448 sd0     RAID6
      0 Online       500107862016 0:0.0   noencl <ST3500320AS SD15>
      1 Online       500107862016 0:1.0   noencl <ST3500630AS 3.AAG>
      2 Online       500107862016 0:2.0   noencl <ST3500320AS SD15>
      3 Online       500107862016 0:3.0   noencl <ST3500320AS SD15>
      4 Online       500107862016 0:4.0   noencl <ST3500320AS SD15>
      5 Online       500107862016 0:5.0   noencl <ST3500320AS SD15>

# sysctl hw.sensors.arc0
hw.sensors.arc0.drive0=online (sd0), OK

 From /etc/sensorsd.conf

drive:command=echo "%t failed with status: %s %2 on %x" | mail -s 
"`hostname` sensorsd CRITICAL \(RAID\)" alarm



Stuart Henderson wrote:
quoted text
> On 2008-10-28, Don Jackson <don.jackson@gmail.com> wrote:
>   
>> On Oct 28, 2008, at 3:47 PM, Robert Franklin wrote:
>>
>>     
>>> Did you read the man page for arc(4)? It says right there.
>>>       
>> I did, and I'm not seeing anything.
>>     
>
> ...
>      arc supports alarm control and monitoring of volumes configured on the
>      controllers via the bio(4) interface and the bioctl(8) utility.
> ...