Troubleshooting vSphere Storage

The vSphere Pluggable Storage Architecture

The vSphere Pluggable Storage Architecture is essentially a collection of plugins that reside inside the VMkernel layer of an ESXi host. The following figure shows a graphical representation of all the components of the PSA. The top-level plugin in the PSA is the Multipathing Plugin (MPP). The MPP defines how vSphere will manage and access storage including load balancing, path selection, and failover. The MPP itself can be provided by the storage vendor (IE EMC PowerPath) or you may also use the VMware provided Native Multipathing Plugin (NMP).

So essentially, the VMware provided NMP is in itself a MPP. The NMP is loaded by default for all storage devices, however, it can be overridden and replaced by ...