[dm-devel] multipath and san fabric
James Smart
James.Smart at Emulex.Com
Mon Nov 13 19:54:15 UTC 2006
Yep - Ed caught my typo.... :)
-- james
Philip R. Auld wrote:
> Rumor has it that on Mon, Nov 13, 2006 at 02:39:08PM -0500 Edward Goggin said:
>> 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
>>
>
> That's exactly what James's example 2 describes. It's just
> typo'd in the DM paths list.
>
>
>
>>> -----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
>>>>
>>> --
>>> 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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