[dm-devel] multipath and san fabric
Edward Goggin
egoggin at emc.com
Mon Nov 13 19:39:08 UTC 2006
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 at redhat.com
> [mailto:dm-devel-bounces at redhat.com] On Behalf Of James Smart
> Sent: Monday, November 13, 2006 2:18 PM
> To: jslittl at hendricks.org; device-mapper development
> Subject: Re: [dm-devel] 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 at redhat.com
> > https://www.redhat.com/mailman/listinfo/dm-devel
> >
>
> --
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>
>
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