Re: Advice for implementation of LED behavior in Ceph ecosystem

[John Spray <john.spray@redhat.com>]

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