You may want to also cross connect across the 2 target controllers (A,B) in case 2. Doing so provides more redundancy for asymmetric arrays and better resource utilization in case of a failure of either an HBA or target controller which would otherwise prevent utilization of the other HBA or target controller for that LU when load sharing I/O across multiple paths. So the I_T nexus's for the 4 paths are: HBA1_TargetPort1 HBA1_TargetPort3 HBA2_TargetPort2 HBA2_TargetPort4 > -----Original Message----- > From: dm-devel-bounces@xxxxxxxxxx > [mailto:dm-devel-bounces@xxxxxxxxxx] On Behalf Of James Smart > Sent: Monday, November 13, 2006 2:18 PM > To: jslittl@xxxxxxxxxxxxx; device-mapper development > Subject: Re: multipath and san fabric > > If the hba's are on different fabrics - why would you ever put an hba > that is not in the fabric in a zone in that fabric ? (e.g. > your second > option makes no sense). > > If you are stating that the 2hba's are on different fabrics > (and in zones > within those fabric) - but they are seeing the same Storage > device on both > fabrics - then the dm config (note: I'm not talking about > zoning anymore) > would have a path per I_T nexus. I state it this way to > account for dual-ported > controllers, which may appear as separate targets, may exist > within the fabric. > > Example 1: > Fabric A contains HBA1 and TargetPort1. Typically a zone > would exist > within Fabric A that contains these 2 ports. > Fabric B contains HBA2 and TargetPort2. Typically a zone > would exist > within Fabric B that contains these 2 ports. > The storage array contains 2 controllers with 1 port per > controller, or > is a single controller with 2 ports. Either way, the two > ports are > TargetPort1 and TargetPort2, are on the same array, and > all storage > can be seen from any port. > -- > This would have 2 DM paths. > The I_T nexus's are: > HBA1_TargetPort1 > HBA2_TargetPort2 > > Example 2: > Fabric A contains HBA1, TargetPort1, and TargetPort3. > Typically a zone > would exist within Fabric A that contains these 3 ports. > Fabric B contains HBA2, TargetPort2, and TargetPort4. > Typically a zone > would exist within Fabric B that contains these 3 ports. > The storage array contains 2 controllers, with 2 ports per > controller. > Meaning TargetPort1 and TargetPort2 are on controller A, > and TargetPort3 > and TargetPort4 are on controller B. The ports are cross > connected on > the fabrics for redundancy. All storage can be seen from > any port. > -- > This would ahve 4 DM paths > The I_T nexus's are: > HBA1_TargetPort1 > HBA1_TargetPort2 > HBA2_TargetPort3 > HBA2_TargetPort4 > > -- james > > John Little wrote: > > Hi all > > > > Admittedly this is not the correct forum for this question > but I have googled > > this and the only people I have to ask around here are > people who won't touch > > it because it is Linux. > > > > My question is this: I'm using SLES10 with two emulex > hbas, one connected to > > fabric a and one to fabric b. When zoning the switch for > the hbas do I put > > in only one path to the fabric per hba or do I put in two, > one to each of the > > separate fabrics? > > > > Again I realize this is not exactly the correct forum but > since I couldn't > > find an answer anywhere else I figured you guys would be the most > > knowledgeable. If there are some docs somewhere that you > could point me to I > > would appreciate it. > > > > John > > > > -- > > dm-devel mailing list > > dm-devel@xxxxxxxxxx > > https://www.redhat.com/mailman/listinfo/dm-devel > > > > -- > dm-devel mailing list > dm-devel@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/dm-devel > > -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
