July 05, 2015

MPP - Multipathing Plug-in

MPP - Multipathing Plug-in

The top-level plug-in in Pluggable Storage Architecture (PSA) is the Multipathing Plug-in (MPP). The MPP can be either the internal MPP, which is called the Native Multipathing Plug-in (NMP), or a third-party MPP supplied by a storage vendor. In ESXi storage is accessed through a VMware built-in MPP (NMP) or a third-party MPP.

VMware’s Native Multipathing Plug-in is also a MPP.

The process for connecting a storage array to VMware includes:
  • Check the VMware Hardware Compatibility List (HCL) to determine if it is a supported array
  • Use the built-in NMP to handle multipathing and load balancing, if in the HCL
  • Use a supported third-party MPP, if there is need for additional functionality  provided by the MPP
Third-party MPP solutions such as Symantec DMP and EMC PowerPath/VE, replace the behavior of the NMP, SATP, and PSP. It takes control of the path failover and the load-balancing operations for specified storage devices. Third-party MPPs might provide better load-balancing performance than the built-in NMP solution.

The MPP module replaces the NMP, SATP, and PSP.

“The MPP can change the path selection normally handled by the PSP. As a result, it can provide more sophisticated path selection, notable performance increases or other new functionality not present in vSphere by default."

MPPs can coexist with NMP.

A storage path is a possible route from an initiator to a given LUN through which the I/O may travel. A path can be in one of the following states:

Path State
Description
Active A path via an Active storage controller. The path can be used for I/O. Operational and in use.
Standby A path via a Passive or Standby storage controller. The path can be used for I/O if active paths fail. Operational but not in use.
Disabled Path has been administratively disabled, usually by the vSphere Administrator.
Dead Path cannot be used for I/O.
Unknown Path is in unknown error state.

Reference:

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