From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [dm-devel] [PATCH] [RESEND] scsi_dh_alua: Add module parameter to allow failover to non preferred path without STPG Date: Thu, 11 Apr 2013 15:58:36 -0700 Message-ID: <1365721116.6982.3.camel@dabdike> References: <8255ED565A0EAA4A960625E27D49DBF21FF97F35@SACEXCMBX04-PRD.hq.netapp.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: 7bit Return-path: Received: from bedivere.hansenpartnership.com ([66.63.167.143]:43250 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761178Ab3DKW6i (ORCPT ); Thu, 11 Apr 2013 18:58:38 -0400 In-Reply-To: <8255ED565A0EAA4A960625E27D49DBF21FF97F35@SACEXCMBX04-PRD.hq.netapp.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: "Stewart, Sean" Cc: device-mapper development , "linux-scsi@vger.kernel.org" , "James.Bottomley@suse.de" , "snitzer@redhat.com" On Thu, 2013-04-04 at 14:54 +0000, Stewart, Sean wrote: > Resending with requested rewording of the parameter description. > Currently ALUA device handler sends STPG command during failover and failback. > Failover can be optimized by implicit failover (by not to sending STPG command), when 1 is passed as hwhandler parameter in multipath.conf. ex "2 alua 1". We may need to pass the parameter through module param for alua device handler to optimize failover if incase retain_attached_hwhandler set in multipath.conf and hwhandler is set with non-tpgs device handler ex: '1 rdac'. > > Signed-off-by: Vijay Chauhan > Signed-off-by: Sean Stewart Growl, next time don't hand edit the patch. Humans rarely understand patch language well enough to get it right. I fixed it this time, but this is the last time ... > --- > --- a/drivers/scsi/device_handler/scsi_dh_alua.c.orig 2013-03-27 12:18:35.000000000 +0530 > +++ b/drivers/scsi/device_handler/scsi_dh_alua.c 2013-03-27 13:23:16.000000000 +0530 > @@ -710,6 +710,10 @@ static int alua_set_params(struct scsi_d You actually added an extra line, so the second has to become +710,11 > return result; > } > > +static uint optimize_stpg; > +module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR); > +MODULE_PARM_DESC(optimize_stpg, "Allow use of a non-optimized path, > +rather than sending a STPG, when implicit TPGS is supported (0=No,1=Yes). Default is 0."); > + > /* > * alua_activate - activate a path > * @sdev: device on the path to be activated @@ -731,6 +735,9 @@ static int alua_activate(struct scsi_dev This is mangled, I think ... James > if (err != SCSI_DH_OK) > goto out; > > + if (optimize_stpg) > + h->flags |= ALUA_OPTIMIZE_STPG; > + > if (h->tpgs & TPGS_MODE_EXPLICIT) { > switch (h->state) { > case TPGS_STATE_NONOPTIMIZED: > -- > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html