RE: Portal group discovery

Dan,
 
The RFC is very clear about this. In your option 2 scenario, each router
which provides a path to the target MUST advertise an unique Target
Portal Group Tag (TPGT). The simplest reason is that you have no way to
join connections on different routers into the same iSCSI session.
 
The way you achieve this is implementation-specific.
 
HTH,
Ken

________________________________

From: Dan Bar Dov [mailto:[email protected]] 
Sent: Tuesday, 3 October 2006 20:01
To: [email protected]
Cc: William Studenmund; John Hufferd; Julian Satran
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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