Perfect, thanks for the information. That confirms my suspicion and would be why you are not seeing all of the LUNs.
Per v5.1 ESXi host, you have the following limits (which ever comes first😞
1) Maximum LUNs (256)
2) Maximum paths (1024)
For ESXi 5.1, as seen in the section "Storage Maximums" you will see the following:
1) LUNs per Server: 256
2) Number of total paths on a server: 1024
256 max per host or per target ?
Per host. For ESXi (with its early Linux foundation) has a total count for LUN and/or paths that can't be exceeded regardless of the number of arrays.
For example, the LUN count is controlled by the following Advanced (Software) Setting available via the following breadcrumb trail in the vSphere Client:
1) Configuration > Software > Advanced Settings
2) Disk > Disk.MaxLUN
By default it is 256 (and is also the total maximum).
However, if you exceed 1024 total paths (again per host regardless of the number of arrays) before reaching 256, than that would be the limiting factor instead. So as an example for others that might stumble on this:
1) Lets say I have for each hosts I have (zoned) 8 paths to the VMAX and 8 paths to the VNX
2) Then I would not be able to reach 256 LUNs but instead could only present 128 LUNs
EDIT: Removed comment about vSphere v5.1 maximum paths per LUN (it is 8 when using iSCSI but used FC as an example)