By default, ESXi provides an extensible multipathing module called Native Multipathing Plug-In (NMP).
Generally, the VMware NMP supports all storage arrays listed on the VMware storage HCL and provides a default path selection algorithm based on the array type. The NMP associates a set of physical paths with a specific storage device, or LUN.
For additional multipathing operations, the NMP uses submodules, called SATPs and PSPs. The NMP delegates to the SATP the specific details of handling path failover for the device. The PSP handles path selection for the device.
Typically, the NMP performs the following operations:
- Manages physical path claiming and unclaiming.
- Registers and de-registers logical devices.
- Associates physical paths with logical devices.
- Supports path failure detection and remediation.
- Processes I/O requests to logical devices:
- Selects an optimal physical path for the request.
- Performs actions necessary to handle path failures and I/O command retries.
- Supports management tasks, such as reset of logical devices.
