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Protocol endpoints (PEs) are used as I/O access points from the ESXi host to the Dell Unity system. These endpoints establish a data path on-demand for virtual machines and their respective vVol datastores. vVols must be bound to a PE in order to service I/O, and when the vVol no longer needs to service I/O, the vVol becomes unbound. I/O from VMs is communicated through the PE to the respective vVol datastore on the storage system. A single protocol endpoint can multiplex I/O requests from a large number of VM clients to their Virtual Volumes. PEs are automatically created when host access is configured for vVol datastores. Unisphere includes a page that lists all PEs that currently exist on the system.
The behavior of PEs depends on whether block or file vVol datastores are used. For file vVol datastores, the NAS PE looks similar to an NFS mount point. For each file vVol datastore, a single protocol endpoint is created on each vVols-enabled NAS server, regardless of how many ESXi hosts have access to the datastore. All ESXi hosts share the same PE as a single I/O access point. A file vVol becomes bound to the associated NAS PE every time that VM is powered on. When the VM is powered off, the vVol is unbound from the PE. It is recommended to create at least one vVols-enabled NAS server on each SP for load balancing and high availability purposes.
Figure 13 shows a list of NAS PEs in Unisphere for two datastores.
For block vVol datastores, the SCSI PE looks similar to a proxy LUN. However, unlike NAS PEs, each ESXi host that has access to the datastore has its own set of dedicated SCSI PEs. For each ESXi host that is granted access to a datastore, two SCSI PEs are automatically created for multipathing purposes. If the same host is granted access to another vVol datastore, two additional SCSI PEs are also created. The block vVol will be bound to the associated SCSI PE every time that the VM is powered on. When the VM is powered off, the PE is unbound. SCSI protocol endpoints are like LUN mount points that allow I/O access to vVols from the ESXi host to the storage system. Figure 14 shows a list of SCSI PEs in Unisphere for three hosts.