Hi guys, Reading on how ESXi handles multipathing and what involves in it, I came across various terms like NMP, SATP and PSP.
As I understand so far NMP is native multipathing plug-in that is overall responsible for multipathing, failover and load balancing. Within NMP there is SATP (storage array type plug-in) and PSP (path selection policy). SATP is responsible for failover when a particular path to storage (like VMHBA32:C0:T0:L0) goes down and PSP is responsible for how path selection is determined (MRU, Fixed and RR).
I can see below SATP exists on my host.
Name Default PSP Description ------------------- ------------- ------------------------------------------ VMW_SATP_MSA VMW_PSP_MRU Placeholder (plugin not loaded) VMW_SATP_ALUA VMW_PSP_MRU Placeholder (plugin not loaded) VMW_SATP_DEFAULT_AP VMW_PSP_MRU Placeholder (plugin not loaded) VMW_SATP_SVC VMW_PSP_FIXED Placeholder (plugin not loaded) VMW_SATP_EQL VMW_PSP_FIXED Placeholder (plugin not loaded) VMW_SATP_INV VMW_PSP_FIXED Placeholder (plugin not loaded) VMW_SATP_EVA VMW_PSP_FIXED Placeholder (plugin not loaded) VMW_SATP_ALUA_CX VMW_PSP_RR Placeholder (plugin not loaded) VMW_SATP_SYMM VMW_PSP_RR Placeholder (plugin not loaded) VMW_SATP_CX VMW_PSP_MRU Placeholder (plugin not loaded) VMW_SATP_LSI VMW_PSP_MRU Placeholder (plugin not loaded) VMW_SATP_DEFAULT_AA VMW_PSP_FIXED Supports non-specific active/active arrays VMW_SATP_LOCAL VMW_PSP_FIXED Supports direct attached devices
Question is what factors determine which SATP plug in and which PSP is used to reach out storage? Does it solely depend on storage array type and model like whether it's EMC VNX etc.? Any other factors that determines this?
Thanks in advance...