ServerNet Cluster Manual

ServerNet Cluster Description
ServerNet Cluster Manual—520575-003
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The ServerNet Cluster Product
The ServerNet Cluster Product
The ServerNet Cluster product is a new interconnection technology for NonStop
S-series servers. This technology enables up to 24 servers to be connected in a group,
or ServerNet cluster, that can pass information from one server to any other server in
the cluster using the ServerNet protocol.
Servers using either of the currently supported system topologies (Tetra 8 and Tetra
16) can participate in a cluster.
ServerNet clusters extend the ServerNet X and Y fabrics outside the system boundary
and allow the ServerNet protocol to be used for intersystem messaging. A ServerNet
cluster consists of individual servers, each containing internal ServerNet fabrics (X and
Y). These servers are connected to other servers through fiber-optic cables and 6770
ServerNet Cluster Switches. The cables and ServerNet switches constitute the
external ServerNet X and Y fabrics.
ServerNet clusters allow multiple multiprocessor systems to work together and appear
to client applications as one large processing entity.
Three Network Topologies Supported
The network topology refers to the shape of a LAN or WAN and how its components
are organized. The ServerNet Cluster product, when used with 6770 ServerNet Cluster
Switches, uses three types of topologies to support a cluster: a star topology, a split-
star topology, and a tri-star topology.
In all three topologies, each node has two independent connections (the X and Y
fabrics) to two independent cluster switches. The loss of a node does not affect the
other nodes in the cluster.
Figure 1-1 shows diagrams of the supported network topologies. The shaded areas
indicate a star group within a topology.