Re: Advice for implementation of LED behavior in Ceph ecosystem

[Mark Nelson <mnelson@redhat.com>]

On 04/01/2015 04:55 PM, John Spray wrote:
> On 01/04/2015 22:17, John Spray wrote:
>> Once you have found the block device and reported it in the OSD
>> metadata, you can use that information to go poke its LEDs using
>> enclosure services hooks as you suggest, and wrap that in an OSD
>> 'tell' command (OSD::do_command).  In a similar vein to finding the
>> block device, it would be a good thing to have a config option here so
>> that admins can optionally specify a custom command for flashing a
>> particular OSD's LED.  Admins might not bother setting that, but it
>> would mean a system integrator could optionally configure ceph to work
>> with whatever exotic custom stuff they have.
> One more thought occurs to me -- one of the main cases where you'd want
> to flash an LED would be to identify the drive of an OSD that is
> down/out due to a dead drive.  In that instance, the ceph-osd process
> wouldn't actually be running, so you wouldn't be able to send it the
> 'tell' to flash the LED.
>
> I guess in this interesting case you could either:
>   * Allow other OSDs on the same host to handle the 'tell blink' command
> for the dead OSD's drive
>   * Leave this to calamari/whoever to read the dead OSD's block device
> path from "ceph osd metadata", and go blink the LEDs themselves.
>
> Cheers,
> John
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It seems to me that the OSD potentially would flash the LED on it's way 
down if it thinks it's drive is dead/dying?

Mark