From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tore Anderson Subject: Re: Using different configuration for arrays with identicalvendor/product Date: Sat, 29 Mar 2008 00:07:07 +0100 Message-ID: <47ED7A1B.2020508@linpro.no> References: <47ECD532.5060402@linpro.no> <218DC19ED27F8842B837598EC6D59D0ED702BC@CORPUSMX40A.corp.emc.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <218DC19ED27F8842B837598EC6D59D0ED702BC@CORPUSMX40A.corp.emc.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: device-mapper development List-Id: dm-devel.ids * berthiaume_wayne@emc.com > You should be able to use the emc_handler for both arrays. > Depending on the distro you are using only implicit ALUA is supported, > explicit ALUA is in being worked on for upcoming distros. Whether the > storage group within the array attached to the server is ALUA or not is > determined by the failover mode you set for the host on that array. At > the server side you will not know the difference between the two > failover modes, PNR or ALUA. Hi Wayne, thanks for your reply. So I can use the emc_clariion hardware handler towards an array configured for ALUA mode. Wasn't aware of that. I feel it's better to let the array handle the trespassing on its own based on the ratio of =C2=ABnon-optimal=C2=BB I/O operations (using hardware_handler 0), but I = can live with host-initiated trespasses on PG swithces/inits. Anyway - there's still the problem of the path_checker. If I'm using =C2=ABemc_clariion=C2=BB for the array configured for ALUA mode (CLARiiON= Open, mode 4), all paths is perceived to be failed. If I'm using =C2=ABtur=C2=BB= for the array configured for PNR mode (CLARiiON Open, mode 1), the passive path is perceived to be failed. Hence, if I use =C2=ABemc_clariion=C2=BB I won't be able to access the vo= lumes on the CX3-40 at all, while if I use =C2=ABtur=C2=BB dm-multipath won't swit= ch PGs when there's a (real) failure on the active path to the CX200. None of these are acceptable alternatives for production use, so the only workaround I've found so far is to configure the CX3-40 to use PNR mode (which sucks since ALUA is way better). Do you have another trick up your sleeve for me? Regards --=20 Tore Anderson