Simple definition
Linux Device Mapper Multipath combines multiple paths to the same SAN volume for failover and optional I/O load balancing.
Purpose and use
DM Multipath provides coherent access to a volume reachable through multiple compatible block-storage paths.
How does it work?
It groups paths to the same device and applies selection and failover policies.
Example and verification
Verify volume identity, path health and behavior during a planned link-loss test.
Points to watch
Multiple paths to one volume are not multiple data copies. Configuration must match storage-system guidance.
In short
Multipathing manages redundant volume access rather than replacing data redundancy or backup.