From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.12.11.20060308/8.12.11) with ESMTP id k6HEXnRa009565 for ; Mon, 17 Jul 2006 10:33:49 -0400 Received: from bob.fastenal.com (bob.fastenal.com [205.243.112.24]) by mx3.redhat.com (8.13.1/8.13.1) with ESMTP id k6HEXgUw030980 for ; Mon, 17 Jul 2006 10:33:42 -0400 Message-ID: <44BB9FBC.4080700@fastenal.com> Date: Mon, 17 Jul 2006 09:33:32 -0500 From: Kelly Sauke MIME-Version: 1.0 Subject: Re: AW: AW: [linux-lvm] SAN setup with host mirrored disks References: <7CA7BBF7F95AA245ACAB8E28A6285EB905191DB3@s01edv50.warema.de> In-Reply-To: <7CA7BBF7F95AA245ACAB8E28A6285EB905191DB3@s01edv50.warema.de> Content-Transfer-Encoding: quoted-printable Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="iso-8859-1"; format="flowed" To: LVM general discussion and development Fiederling, Daniel wrote: > Currently I have only one path to each disk but further on I'd like to te= st a setup with multiple paths. But am I right that I have to use md on top= of multipathd for getting the two disks mirrored? > =20 Yes, multipathd only handles the multiple paths on a per disk basis. If=20 you need them mirrored you have to use something on top of the multipath=20 layer. Using md is one option that should work just fine.=20 > I tested different qla2xxx drivers (SuSE shipped, origanal download packa= ges from qlogic, packages from hp) and the non suse offered much more modul= e parameters - one of them was about en-/disabling failover. I would guess = that the qla2xxx driver or the card firmware can handle multiple paths. But= I'm not sure about that... > > > =20 I've yet to meet an HBA that doesn't work with multiple paths. I would=20 check EMC's support matrix for your particular card. I know that we=20 have to run specific EMC firmware on our HBAs to be fully supported. I=20 think by running the non EMC firmware you lose some of the functionality=20 and may run into some stability issues. I can't comment on that further=20 since we've never done any testing with non-EMC firmware. > -----Urspr=EF=BF=BDngliche Nachricht----- > Von: linux-lvm-bounces@redhat.com [mailto:linux-lvm-bounces@redhat.com] I= m Auftrag von Kelly Sauke > Gesendet: Montag, 17. Juli 2006 15:36 > An: LVM general discussion and development > Betreff: Re: AW: [linux-lvm] SAN setup with host mirrored disks > > =20 >> Why do I have to expect io errors when using md? What is special about t= he Clariion setup? I would expect that the san disks are only "normal" scsi= disks for linux... >> =20 >> =20 > The difference comes in how the multiple paths to the same disk are=20 > handled under linux. If you only have one path to each disk, then this=20 > doesn't apply to you. I guess I forgot to clarify if you had more than=20 > one path. Anyway, if you have multiple paths mpio knows which is the=20 > Active path and which is the Passive path. Sending IO down a passive=20 > path will result in IO errors. > > > _______________________________________________ > linux-lvm mailing list > linux-lvm@redhat.com > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ > =20