Cliques
A
clique is a set of Teradata nodes that share a common set of disk
arrays. Cabling a subset of nodes to the same disk arrays creates a
clique.
In the event of node failure, virtual processors on the failed node can
migrate to another available node in the clique to keep the system
operational. Access to all data is maintained. In order for the vprocs to
migrate, all nodes in a clique must have access to the same disk arrays.
The diagram on the facing page shows a twelve-node system consisting
of three cliques, each containing four nodes. Because all disk arrays are
available to all nodes in the clique, the AMP virtual processors will retain
access to their responsible rows.
In the event of three out of four nodes failing, the remaining node would
attempt to absorb all virtual processors from the failed nodes. Because
each node can support a maximum of 128 virtual processors, the total
number of virtual processors for the clique should not exceed 128.
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