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

[Sebastian Herbszt]

From: "Tore Anderson"
> Unfortunately I have found no way to detect if an array is operating in
> ALUA or PNR mode and have dm-multipath automatically apply different
> device{} sections based on that.  I have some nodes that are connected
> to both my CX3 and an old CX200 (which doesn't support ALUA), and due to
> this I need to use PNR mode on the CX3 too, wich kinda sucks.  Time to
> get rid of the CX200 I guess.

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?

- Sebastian