I have a dell equallogic PS4000XV connected to a physical server running ESXi 4.1 (not update 1).
The SAN hosts about 10 LUNs, all of which are initiated on the ESXi server using two pNIC on a vSwitch.
For all but the two most recently created LUNs, there are two paths (in round-robin) working in MPIO. The two most recently created LUNs only seem to have one path (in Storage adapters -> iSCSI Software Adapter -> right click and 'manage paths').
How can this be? what happened to the additional path? Do you think it's because of my SAN, or because of some configuration problem in my ESXi 4.1?
Have you defined 2 vmkernels with 2 ipaddresses and configured nic-binding?
If you have a enterprise og enterprise plus, equallogic has a MPIO-plugin that configures everything for you.
I had this issue a while back after I installed the equallogic plugin and used it to configure access to the equallogic.
After discussing this with Dell support I had it explained to me.
it all depends on the number of enclosures that your volumes span. If it spans only 1 enclosure you will only get 2 paths to that volume. If it spans more than one you will get more paths.
This got looked messy as on some luns we where seeing some paths used and other luns had other paths used.
the document I attached has following entry that explains it a bit...
have a look at page 3-1
When determining how many sessions to create to a volume, EHCM chooses a value that meets all constraints specified by the totalsessions, volumesessions and membersessions values.
hope this helps...