Storage Array Type Plug-ins (SATPs) are responsible for array-specific operations. The SATPs are submodules of the VMware NMP.
ESXi offers an SATP for every type of array that VMware supports. ESXi also provides default SATPs that support non-specific active-active, active-passive, ALUA, and local devices.
Each SATP accommodates special characteristics of a certain class of storage arrays. The SATP can perform the array-specific operations required to detect path state and to activate an inactive path. As a result, the NMP module itself can work with multiple storage arrays without having to be aware of the storage device specifics.
Generally, the NMP determines which SATP to use for a specific storage device and associates the SATP with the physical paths for that storage device. The SATP implements the tasks that include the following:
Monitors the health of each physical path.
Reports changes in the state of each physical path.
Performs array-specific actions necessary for storage fail-over. For example, for active-passive devices, it can activate passive paths.
ESXi includes several generic SATP modules for storage arrays.
SATP for local direct-attached devices.
As of vSphere 6.5 Update 2 release, VMW_SATP_LOCAL provides multipathing support for the local devices, except the devices in 4K native format. To claim multiple paths to the local devices, you are no longer required to use other SATPs as you were in the earlier vSphere releases.
VMW_SATP_LOCAL supports the VMW_PSP_MRU and VMW_PSP_FIXED path selection plug-ins, but does not support VMW_PSP_RR.
For more information, see the VMware Compatibility Guide and the vSphere Command-Line Interface Reference documentation.