Re: iSCSI: rev07 - ISID-TSID & naming comments

["Mallikarjun C." <cbm@rose.hp.com>]

Jim,

>Did I make any thing more clear or just muddle things up?

Thanks for the explanation, yes it does help me to see your 
thinking.  This is what I suspected you meant, but wanted to 
be sure.

Regards.
--
Mallikarjun 


Mallikarjun Chadalapaka
Networked Storage Architecture
Network Storage Solutions Organization
MS 5668	Hewlett-Packard, Roseville.
cbm@rose.hp.com



>Mallikarjun,
>
>My "text" again isn't conveying what I'm thinking, but yours is closer.  I
>want the model to allow physical things to span multiple virtual things.
>What I was trying to convey is exactly what you're saying.  Is it more
>clear if I had said "can live in multiple portal groups *so long as each
>portal group was in a different node*"?  But I want a network portal (be it
>either physical or virtual) to "connect up" to different nodes (through
>unique portal groups on each node).
>
>If a network portal has only one ipaddress/[tcpport], it can service
>multiple nodes, but belong to only one portal group per node.  So, maybe
>this multi-node (focused on only one network portal) picture helps:
>
>    NodeA           NodeB          NodeC
>      |               |              |
>PortalGroupA1   PortalGroupB2  PortalGroupC1
>      |               |              |
>      |_________NetworkPortalX_______|
>            (Ipaddress/[tcpport])
>
>
>The picture doesn't show other portal groups that might be in any of the
>nodes nor does it show other network portals that might be in any of the
>portal groups.   This is the tree view from a given network portal up.
>The up-degree at the network portal can be anything.  The up-degree of each
>portal group is one.  There's a different view from the node down.   In the
>node-down graph, I can have any number of portal groups below a node and
>any number of network portals in each portal group.  The rule is that this
>graph is a tree.
>
>And the model allows the leaf structure of one node-down tree to be related
>in any way to the leaf structure of another node-down tree.  [I'm finding
>it hard to describe this clearly.]  By example:  suppose that PortalGroupA1
>above had another NetworkPortalY in it (within NodeA).  This network portal
>need not be in PortalGroupB2 of NodeB just because NetworkPortalX was in
>PortalGroupB2 .  So the fact that two leaves of one node-down tree are in
>one portal group (have a common parent) does not require those two leaves
>to be in the same portal group (have a common parent) of another node-down
>tree.
>
>Did I make any thing more clear or just muddle things up?
>
>And yes, the scope of the portal group tag is the node.
>
>The tricky part in this is the viewpoint.  If you think only one node at a
>time, then the node-down tree is easy enough to describe.  It's when you
>try to put more nodes in the picture that the relationships get more
>complicated.   I'm not even sure it's possible in 2D to render in one graph
>the full set of possibilities even with two nodes!
>
>Jim Hafner
>
>
>"Mallikarjun C." <cbm@rose.hp.com> on 08/15/2001 10:40:16 am
>
>Please respond to cbm@rose.hp.com
>
>To:   Jim Hafner/Almaden/IBM@IBMUS
>cc:   ips@ece.cmu.edu
>Subject:  Re: iSCSI: rev07 - ISID-TSID & naming comments
>
>
>
>Jim,
>
>As you say, I too think we are very close on this.  Let me comment
>on one sentence in your message that I didn't quite follow.
>
>>Perhaps if we can make it clear that a
>>network portal can live in multiple portal groups, but a portal group only
>>belongs to one iSCSI node, then we're OK.
>
>Two comments -
>- My understanding of portal groups has been that they are disjoint
>  sets, and that's the reason a session could not span multiple portal
>  groups.  You seem to suggest that portal groups are overlapping sets
>  with possibly common network portals, or did I misunderstand?
>
>- By saying "a portal group only belongs to one iSCSI node", if you
>  are implying that the scope of the portal group tags is per iSCSI
>  node (i.e. the tags are unique and meaningful within one iSCSI node),
>  then I am fine.  I just want to confirm that you are not excluding the
>  possibility of one *physical* portal group (say an HBA) being able
>  to get to multiple (virtual) iSCSI nodes.
>
>Regards.
>--
>Mallikarjun
>
>
>Mallikarjun Chadalapaka
>Networked Storage Architecture
>Network Storage Solutions Organization
>MS 5668   Hewlett-Packard, Roseville.
>cbm@rose.hp.com