Multipath IO is the ability to address the same storage device over multiple connections, providing improved reliability and availability. This concept is not new to Linux. Multipath capabilities exist in the volume management layer, SCSI upper level, and in the SCSI lower level device driver. This paper examines an approach to providing multipath support in the Linux 2.5+ SCSI mid-level. An implementation at this level gives the reduced resource usage and better performance of lower level implementations, along with the device independent capabilities of upper level implementations.
The target audience is developers knowledgeable about SCSI or Linux SCSI internals that are also interested in multipath storage support.