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@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
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