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14.4TB Virtualization SAN MPIO connections?!

Frequent Advisor

14.4TB Virtualization SAN MPIO connections?!


I have a new 2 node LeftHand SAN. I have configured everything in a standard cluster with a VIP but am trying to verify a few pieces...

I have 2 physical Windows Server 2008 R2 64 Bit servers which have 2 NIC's for iSCSI. I have configured each one with an IP. I have then installed the LeftHand DSM MPIO framework, which also installs the Server 2008 MPIO feature.

After a restart I have configured a LUN as per the LeftHand guide.. but have a few questions:

Firstly the Windows Solution Pack User guide says each LUN should have a path per storage node plus an administrative path. (Which I cannot see even in their document)...

So I have 2 storage nodes, and 2 network cards, so I am assuming I should see 5 paths:

NIC 1 -> Storage Node 1
NIC 1 -> Storage Node 2
NIC 2 -> Storage Node 1
NIC 2 -> Storage Node 2
Administrative path

However I just see 4 paths, is this normal??

The strange thing is that 2 of the paths have CHAP enabled, and 2 do not... I am not using CHAP so what are these?

In the CMC under the Gateway Connection, I can see 4 connections for this LUN, for example:

Storage Node 1, DSM
Storage Node 2, DSM
Storage Node 1
Storage Node 1

Finally the other question is that the LUN's being allocated to ESX do not have the 2 DSM entries per host? They have just 2 entries pointing to the same storage node. Is this correct?

If I look at the LUN's I can see that it appears to be splitting them up so that storage node 1 is responsible for some, and storage node 2 is responsible for others..

One very confused person...

Re: 14.4TB Virtualization SAN MPIO connections?!

The DSM for the P4000 currently only supports active/passive. So your Primary path NIC will be seen connected to both nodes - the other NIC will only be connected to one node (referred to as the administrative connection) in case there is a failure on the primary path. You can define different primary paths on a per lun basis - still acting as active\passive - but utlizing both NICs. Active/Active MPIO functionality will be available in SAN/iQ 9.

ESX does not have a DSM. The ESX host will make a connection per LUN to one node. The P4000 will load balance the connections to luns (gateway connections).
Frequent Advisor

Re: 14.4TB Virtualization SAN MPIO connections?!


Thanks for the reply...

From what you are saying the ESX side seems to be configured correctly. I have two paths which would indicate each NIC connecting to a single storage node, which I can see in the CMC. You mention the P4000 will load balance the connection, is this done dynamically, e.g. every few hours the initiator will talk to the VIP and it will say go to Storage Node 1, or go to Storage Node 2 etc, or is this just done once at initial discovery? Or is it simply that if I have 10 LUN's on my 2 node cluster, 5 will use Storage Node 1, and 5 will use Storage Node 2??

I am not sure if I am understanding the DSM stuff... All I can see on both sides is 4 paths, should I be seeing 5??