The clique is a feature of some MPP systems that physically group nodes together by multiported access to common disk array units. Inter-node disk array connections are made using FibreChannel (FC) buses.
FC paths enable redundancy to ensure that loss of a processor node or disk controller does not limit data availability.The nodes do not share data. They only share access to the disk arrays. The following figure illustrates a four-node clique:
A clique is the mechanism that supports the migration of vprocs under PDE following a node failure. If a node in a clique fails, then vprocs migrate to other nodes in the clique and continue to operate while recovery occurs on their home node. For more detailed information on vprocs see Virtual Processors.
PEs that manage TPA-hosted physical channel connections cannot migrate because they are dependent on the hardware that is physically attached to the node to which they are assigned.
PEs for workstation-attached TCP/IP connections do migrate when a node failure occurs, as do all AMPs.