VMWare licensing for multipathing

I just wanted confirmation that I am not misunderstanding this, but if I were to buy the VMWare vSphere Essentials Plus kit, since it says it does not include the vStorage APIs for Multipathing, then I will only have one path to my FC SAN from each host.   Is this correct?  

Assuming so, and there is only one physical connection to each host, is vCenter smart enough to switch ownership of the VMs to the other host using HA if the connection to the SAN is lost (via HBA failure for example)?  I currently have 2 servers in a cluster.  
B1izzardAsked:
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bleeuwenConnect With a Mentor Commented:
•vStorage APIs for Multipathing — A framework for storage partner multipathing plug-ins that is integrated with the standard VMware Ready HCL certification program. The vStorage APIs for Multipathing provide an I/O multipathing framework that allows storage partners to create Multipathing Extensions Modules that plug in to VMware ESX/ESXi to deliver storage path failover and storage I/O throughput optimized for partners' storage arrays. Through the VMware Ready certification program storage partners certify their Multipathing Extensions Modules for support with VMware ESX/ESXi.

Check the HCL (http://www.vmware.com/resources/compatibility/search.php?q=vmware%20hcl) if your SAN is supported. If it is, it will support multipathing.
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Andrew Hancock (VMware vExpert / EE MVE^2)Connect With a Mentor VMware and Virtualization ConsultantCommented:
In answer to your question, you have a single path from ESX host to SAN.

Yes, in HA the ESX host will bring-up and power-on the Virtual Machines in the cluster it has via it's SAN single patch connection.
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B1izzardAuthor Commented:
>>Yes, in HA the ESX host will bring-up and power-on the Virtual Machines in the cluster it has via it's SAN single patch connection.

So to be perfectly clear, if host A has all the VM's and it fails, HA will restart the VM's on host B.  Please correct me if I have this wrong.
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coolsport00Connect With a Mentor Commented:
As "hanccocka" mentions, you do have only 1 path. But, to answer more specifically your "HA" question, keep in mind that vCenter does not play a part in HA except to configure it. HA works independently of vCenter once it is configured/enabled. Once configured, hosts have an agent installed and running on them. At that point, it's the HA agent on the hosts that basically starts  tracking heartbeats and takes action when one of the other hosts in the cluster appears to be down. During an HA event, vCenter does not need to be running in order for the VMs to be powered up on another ESX/i host. vCenter is required for VMotion, but VMotion is not involved with HA unless you are licensed for it and have vMotion configured in your cluster. HA simply registers the VMs on another host and then powers them back up. Shared storage is necessary of course...all the hosts in the cluster have to be able to access the virtual machine's files. So even if the host that vCenter resides on goes down, with HA, one of the remaining ESX hosts will try to register that vCenter VM and power it back up.

Regards,
~coolsport00
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cdjcConnect With a Mentor Commented:
If you zoned up your FC SAN paths properly, with both redundant HBAs, redundant SAN controllers, and redundant SAN switches, then you should have more than one path available to you on your hosts.  Storage traffic will be going to down a single path at any given moment, but you will have more than one path available for failover purposes, if one were to fail.

vStorage APIs for Multipathing are used if you wish to take advantage of vendor-specific multipathing features, and requires MPP's that would be provided by your SAN vendor.  There are basic multipathing features that are provided with the inbox VMware ESX/ESXi product that should be fine for what you want to achieve.

Consult the Fibre Channel SAN Configuration Guide (.PDF) for more information.  One section that would go a bit further to explain this stuff, would be Appendix B - "Managing Multipathing Modules and Hardware Acceleration Plug-Ins".  But, you really should read the entire document.
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cdjcCommented:
Here is some more information about VMware PSA's and NMP's.  It also briefly touches on third-party MPP's (that would require the vStorage APIs for Multipathing):

http://kb.vmware.com/kb/1011375
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B1izzardAuthor Commented:
Thanks.
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