From mboxrd@z Thu Jan 1 00:00:00 1970 From: Erez Zilber Subject: Re: Setting up a multipath device Date: Thu, 04 May 2006 18:28:08 +0300 Message-ID: <445A1D88.7030500@voltaire.com> References: <445A0AE9.20907@voltaire.com> <20060504144915.GA2319@pundit> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20060504144915.GA2319@pundit> 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 Christophe Varoqui wrote: >On Thu, May 04, 2006 at 05:08:41PM +0300, Erez Zilber wrote: > =20 > >>Hi, >> >>I'm new to device mapper and trying to set a multipath target: >> >>I'm connected to the same LUN over iSCSI in 2 paths: >> >>Here's the output of sg_map: >>sg_map -i -x >>/dev/sg0 3 0 0 0 0 /dev/sda DotHill SANnet II FC 411I >>/dev/sg1 4 0 0 0 0 /dev/sdb DotHill SANnet II FC 411I >> >>I ran the following command: >>multipath 2 round-robin 1 0 /dev/sda round-robin 1 0 /dev/sdb >> >> =20 >> >Just start multipathd >or run multipath without params > > =20 > >>If I understand correctly, the 1st priority group contains /dev/sda. Th= e=20 >>2nd priority group contains /dev/sdb. If /dev/sda fails, traffic should= =20 >>automatically move to /dev/sdb. Is that right? >> >>Here's the out put of multipath -l: >> >>3600c0ff00000000007c1d121c397f503 >>[size=3D10 GB][features=3D0][hwhandler=3D0] >>\_ round-robin 0 [prio=3D0][active] >>\_ 3:0:0:0 sda 8:0 [active][undef] >>\_ round-robin 0 [prio=3D0][enabled] >>\_ 4:0:0:0 sdb 8:16 [active][undef] >> >>What does 8:0 & 8:16 mean? What is 3600c0ff00000000007c1d121c397f503? >> >> =20 >> >8:0 & 8:16 are paths major:minor numbers >3600c0ff00000000007c1d121c397f503 is the multipath name. >consider activating the fancy naming option in the config file. >=20 > =20 > >>Now, assuming that what I did so far is ok, how do I use the multipath=20 >>device? Do I use /dev/sda (or /dev/sdb)? >> >> =20 >> >You should use /dev/mapper/3600c0ff00000000007c1d121c397f503 >=20 >Regards, >cvaroqui > >-- >dm-devel mailing list >dm-devel@redhat.com >https://www.redhat.com/mailman/listinfo/dm-devel > =20 > Thanks. It seems to work now. Anyway, I have some more questions: 1. Was it wrong to run 'multipath 2 round-robin 1 0 /dev/sda round-robin 1 0 /dev/sdb'? 2. If I don't supply any parameters, how does the dm know which devices are the same physical device (that /dev/sda & /dev/sdb are the same physical device)? 3. How are the priority groups defined if no parameters are supplied? 4. What is the timeout for a device that has failed? When does the dm move to the next priority group? Thanks --=20 ____________________________________________________________ Erez Zilber | 972-9-971-7689 Software Engineer, Storage Team Voltaire =96 _The Grid Backbone_ __ www.voltaire.com