From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim Pepper Subject: Re: Question about Request Sense case in scsi_lib.c Date: Tue, 12 Oct 2004 09:31:06 -0700 Sender: linux-scsi-owner@vger.kernel.org Message-ID: References: <20041012000058.GA26569@osdl.org> Reply-To: Tim Pepper Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from rproxy.gmail.com ([64.233.170.197]:59941 "EHLO mproxy.gmail.com") by vger.kernel.org with ESMTP id S266195AbUJLQbI (ORCPT ); Tue, 12 Oct 2004 12:31:08 -0400 Received: by mproxy.gmail.com with SMTP id 80so202332rnk for ; Tue, 12 Oct 2004 09:31:06 -0700 (PDT) In-Reply-To: List-Id: linux-scsi@vger.kernel.org To: linux-scsi@vger.kernel.org On Mon, 11 Oct 2004 17:00:58 -0700, Dave Olien wrote: > I'm having some odd behavior with my multipath fibre channel system. > I'm running 2.6.9-rc3, and have a Qlogic 2300 dual ported controller, > routed through two brocade switches to two IBM FastT200 disk arrays. > > The FastT200 are configured as JBOD. Each array has 10 disks. Each FastT200 > is dual ported, configured in "active-active" mode. I thought on FAStT's while there are dual-active controllers, for a given lun they weren't active-active, but rather active-passive with either manual or automatic volume transfer. Assuming automatic volume transfer is on and you send IOs to both controllers simultaneously you would ping-pong the cache, drive IO rates lower and possibly see that manifest itself in interesting behaviour in the linux scsi stack. With manual volume transfer you should get IO errors from the controller which is not active or preferred for the given lun. Maybe somebody involved with their RDAC multipathing driver follows this list and can comment on their intentions for the 2.6 kernel and dm multipathing.