[dm-devel] Re: Round Robin vs Active/Passive

[Tore Anderson]

* Sebastian Herbszt

> The comment and code from libmultipath/prioritizers/emc.c
> 
>  if ( /* Effective initiator type */
>       sense_buffer[27] != 0x03
>   /*
>    * Failover mode should be set to 1 (PNR failover mode)
>    * or 4 (ALUA failover mode).
>    */
>   || (((sense_buffer[28] & 0x07) != 0x04) &&
>       ((sense_buffer[28] & 0x07) != 0x06))
>   /* Arraycommpath should be set to 1 */
>   || (sense_buffer[30] & 0x04) != 0x04) {
>   pp_emc_log(0, "path not correctly configured for failover");
>  }
> 
> doesn't help with the detection part?

Not really, there's no way I can put this into a device{} section to
differentiate between two CLARiiONs running different failover modes.

What I need to do is this:

# My new CX3-40f which supports ALUA (preferred) as well as PNR
device {
	vendor DGC
	product *
	product_blacklist LUNZ
	alua_capable yes
	[..ALUA optimised settings...]
}

# My old CX200, only supports PNR
device {
	vendor DGC
	product *
	product_blacklist LUNZ
	alua_capable no
	[..PNR optimised settings...]
}

...but there's no such thing as the "alua_capable" setting or any other
setting that can be used to distinguish between the two CLARiiONs, as
far as I know, so I have to use both arrays in PNR mode even though the
newest one of them supports ALUA.

Please prove me wrong...  ;-)

Regards,
-- 
Tore Anderson