NonStop Systems Introduction

Glossary
NonStop Systems Introduction—527825-001
Glossary-10
ServerNet cluster
portion of a processor multifunction (PMF) unit, an I/O multifunction (IOMF) unit, or a
ServerNet adapter.
ServerNet cluster. A network of servers (nodes) connected together using the ServerNet
protocol for interprocessor communication across a cluster and within its nodes. A
ServerNet cluster offers linear system expansion beyond the 8-processor or
16-processor limits of a single server, achieving comparable speeds for internal and
external ServerNet communication.
ServerNet cluster switch. A network switch that provides the physical junction point to
enable a NonStop server to connect to a ServerNet cluster.
ServerNet fabric. An interconnected collection of ServerNet routers that provides
communications between processors, and between processors and I/O components in
a single system. In each system, ServerNet fabrics are paired as an X fabric and a Y
fabric for fault tolerance.
ServerNet node. An addressable unit on a ServerNet system area network (ServerNet
SAN), such as a processor or a ServerNet addressable controller (SAC).
ServerNet node ID. A unique identifier for an addressable unit on a ServerNet system area
network (ServerNet SAN). A unit can have multiple ServerNet node IDs. This ID is
used for routing: each packet has a source ServerNet node ID and a destination
ServerNet node ID. A pair of processors operating in duplex mode share one
ServerNet node ID.
ServerNet packet. The unit of transmission in a ServerNet system area network (ServerNet
SAN). A ServerNet packet consists of a header, a variable-size data field, and a 32-bit
cyclic redundancy check (CRC) checksum covering the entire packet. The header
contains fields for control, address, and destination, and source fields to identify the
processor or I/O controller transmitting and receiving the packet.
ServerNet router. An application-specific integrated circuit (ASIC) responsible for providing
interconnection of ServerNet links in a ServerNet system area network (ServerNet
SAN). A ServerNet router is never an end device. A ServerNet router in a NonStop
server has a total of six input and six output ServerNet ports.
service. A function performed by a server process or program on behalf of a requester or
client. A server can perform one or several services.
SQL. See structured query language (SQL).
SQL/MX. The NonStop relational database management system. SQL/MX promotes
efficient online access to large distributed databases.
structured query language (SQL). A relational database language used to define,
manipulate, and control databases.