Transparent file system migration including a method that identifies a source physical storage location in a file system that supports simultaneous access by multiple independent processes. A target physical storage location in the file system is identified and its contents are migrated to the target physical storage location. The migrating includes disallowing new allocations to the source physical storage location and copying contents from the source physical storage location to the target physical storage location. A write request to write data to the source physical storage location is received prior to or during the migrating. The write request is serviced contemporaneously with the migrating. Read and write requests directed to the source physical storage location are redirected to the target physical storage location. The redirecting is responsive to the migrating completing. The requests are from the multiple independent processes and include both logical and physical input/outputs.