RE: Portal group discovery

Dan,

The portal groups have to share more than a target name - they'll have to 
have some common state (the CmdSN etc.).
If behind the routers there is only the "real" FC target I don't see how 
you can build a portal out of several routers. If the target function is 
in the "real target" it might as well know who all its front-ends are.

Julo



"Dan Bar Dov" <[email protected]> 
03/10/06 12:00

To
<[email protected]>
cc
"John Hufferd" <[email protected]>, Julian Satran/Haifa/IBM@IBMIL, 
"William Studenmund" <[email protected]>
Subject
RE: [Ips] Portal group discovery






Let me try to explain how it can and does happen.
 
Our iSCSI target device is a "gateway" (or router). It provides FC SAN 
targets to iSCSI SAN. The iSCSI target name is generated from the FC WWNN.
 
When there are more then one such routers in the iSCSI SAN, it is possible 
and normal
for two (or more) iSCSI routers to expose the same FC target. This is not 
by mistake,
rather, it allows fail-over between such routers, where the initiator uses 
the multiple portals
for failover.
 
Given such a configuration, how does the initiator discover it?
option 1: the routers have "cluster awareness", one router can combine 
information from the whole
router cluster for sendTargets response.
option 2: the initiator is configured with multiple discovery addresses - 
one per router.
 
If option 2 is used, then the initiator needs to combine information 
discovered in discrete sendTargets
responses and produce portal groups.
 
My question relates specifically to that situation - it is not clear from 
the iSCSI spec, if such failover 
between portals (with the same pgt) discovered in discrete sendTargets 
responses is allowed.
 
Thanks,
Dan
 
 

From: Julian Satran [mailto:[email protected]] 
Sent: Friday, September 29, 2006 8:05 AM
To: William Studenmund
Cc: Dan Bar Dov; [email protected]
Subject: Re: [Ips] Portal group discovery


This is not supposed to happen (getting partial data in a session) 
If it happens it can be the result of a reconfiguration (between the two 
discovery sessions). 

Julo 



William Studenmund <[email protected]> 
29/09/06 05:31 


To
Dan Bar Dov <[email protected]> 
cc
[email protected] 
Subject
Re: [Ips] Portal group discovery








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On Sep 28, 2006, at 7:59 AM, Dan Bar Dov wrote:

> Is it allowed for an initiator to create a single portal group from 
> information
> collected from two (or more) sendTargets discovery sessions?

I don't think you need two or more SendTargets discovery sessions. 
You are supposed to hear about all portals in one SendTargets 
response, so it's supposed to all be there.

If you had very separate off-load cards, I could see that not being 
followed. But then chances are you can't have a session span said 
cards anyway. :-)

Take care,

Bill
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