"ULP and vSphere Hypervisors such as VMware vSphere use ALUA to communicate with backend storage arrays. ALUA provides multipathing (two or more storage networking paths) to the same LUN on a storage array and marks one path “Active” and the other “Passive.” The status of the paths may be changed either manually by the user or programmatically by the array.
Multipath Considerations for vSphere To maintain a constant connection between a vSphere host and storage, ESX software supports multipathing. To take advantage of this feature, the ESX host requires multiple FC, iSCSI, or SAS adapters and the HPE MSA virtual volumes need to be mapped to these adapters. This can be accomplished easily on the HPE MSA Storage by creating a host definition as outlined in the previous section and associating the World Wide Names (WWNs) of the multiple interfaces (HBA ports) on the host server to this new host object. When mapping a Virtual Volume to the host object in the SMU, all the path mappings are automatically created to support multipath to the host. To do this in the CLI an entry for each path would need to be created or use the Host/Host Groups with wildcards. As recommended in the previous section, HPE recommends configuring the HPE MSA Storage to use a Host Group for a vSphere cluster and use the cluster object when mapping Virtual Volumes. This will create all the mappings to all the adapters to support multipath in the cluster in one step. VMware vSphere supports an active/active multipath environment to maintain a constant connection between the ESX host and the HPE MSA Storage Array. The latest version of vSphere offers 3 path policies: “Fixed,” “Most Recently Used,” and “Round Robin.” HPE recommends using the “Round Robin” preferred selection path (PSP) policy for best performance and load balancing on the HPE MSA Storage. By default, VMware ESX systems use only one path from the host to a given volume at any time. This is defined by the path selection policy call MRU path. If the path actively being used by the VMware ESX system fails, the server selects another of the available paths. Path failover is the detection of a failed path by the built-in ESX multipathing mechanism which switches to another path by using MPIO software, VMware Native Multipathing (NMP), and the HPE MSA firmware. "
The key in the above paragraph here being that HPE recommends you use RR as the preferred policy, but then the MSA firmware does some magic on the backend when it comes to determining which to actually use. I can understand the confusion because it does say active/active in the CLI, but it's not true active/active as the industry definition would state.
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