#VCP #Concept VMkernel multipathing plugin provided by ESXi by default. It matches different sub plugins. ![[_media/vSphere - Storage Protocols-2024-05-14-1.png]] SATP and PSP can be built-in by VMware or provided by a third party. ## Function - Manages physical path claiming and unclaiming - registers and de-registers logical devices - Associates physical paths with logical devices - Processes I/O requests to logical devices - selects optimal physical path (load balance) - performs actions necessary to handle failures and retries ## SATP(Storage Array Type Plugins) responsible for managing path failover for the storage device. Handles detection and recovery of path. There are already default SATPs included inside vSphere for multiple vendors, but you should look for each storage array for specific instructions on SATP definition. - Path monitoring - monitors path and detects any failures and recoveries - Failover and Failback - When a path fails SATP initiates failover to alternative path and failbacks once the path is available again. - Path configuration - Configures path to specific requirements of storage array ## PSP(Path selection Policy) Responsible for distribution of I/O on all available paths. - Load balancing - Distributes I/O across multiple paths to optimize performance - Path selection - chooses best path for each I/O request - Performance optimization - optimizing use of available paths such for latency ### Policies - Round Robin (RR) - requests are distributed evenly across all available paths in round-robin fashion. - Most Recently Used (MRU) - I/O requests continue to be sent down the most recently used path until a failure. - Fixed - I/O requests are always sent down a designated path, if the path fails another is used but is switched back once up again. ## 🔗Resources