···4747Using this device-mapper switch target we can now build a two-layer4848device hierarchy:49495050- Upper Tier – Determine which array member the I/O should be sent to.5151- Lower Tier – Load balance amongst paths to a particular member.5050+ Upper Tier - Determine which array member the I/O should be sent to.5151+ Lower Tier - Load balance amongst paths to a particular member.52525353The lower tier consists of a single dm multipath device for each member.5454Each of these multipath devices contains the set of paths directly to