Oracle Names Servers

Oracle Names server is like a telephone book; it provides an address but not directions to that address. An Oracle Names server will provide a client connection request with an address to connect to, for instance, hostname, port number and service or SID name. Oracle Names involves the use of an Oracle Names server. The Oracle Names server is used to store service addresses and net service names. The Oracle Names server is used to keep a central store of service addresses much like a DNS server does. An Oracle Names server can be used to store names and addresses of all database services across a network. The Oracle Names server is used to return a network address when provided with a name by a client connection request. The client process will then make a connection request to a database server with the network address provided by the Oracle Names server.

Oracle Names server network setup is intended for use on large globally distributed networks. With Oracle Names, network addresses and database links are potentially available to all nodes throughout a very large network. Each node in this network is accessed by use of a simple name where individual regions and Oracle Names servers act as routers to direct traffic between source and target nodes, much like the internet. Network addresses and infrastructure is transparent from the client process perspective. Oracle Names server environments also allow for centralised administration of a network environment.

Very large networks can be divided up into adminsitrative regions. For instance, a global company could divide up their networking environment into administrative regions based on continents such as Europe, North America, Asia, etc. Oracle Names servers can be included within administrative regions. However, Oracle Names servers can also be allowed to communicate across administrative regions. Storage of Oracle Names servers within administrative regions can be stored in a database applicable to that administrative region. When a database is not used multiple Oracle Names server within a single administrative region update each other by way of replication. Obviously storage of Oracle Names servers configurations is more efficiently stored in a centralised administrative region database. Without the database Oracle Names servers will have to continually query each other with respect to network node updates. Domains exist uniquely within an administrative region. Thus domains can be duplicated across administrative regions. Domains are organised in hierarchical structures.

Oracle Names Server Configuration

An Oracle Names server will store specific details about databases within their respective administrative regions and sometimes outside of their administrative regions. In general these values are global database names, other Oracle Names server names and addresses, global database links, Oracle Connection Managers, net service names and aliases. Aliases can be net service alternate names, database service names and global database links.

Domain models for Oracle Names server usage can either consist of a single domain or multiple domains. When using multiple domains with Oracle Names servers all domains must be configured in a hierarchical fashion with a root domain at the top of the hierarchy. The root domain has access to all other domains, allowing different administrative regions to communicate with other administrative regions through the root domain; each domain has its own configuration set up or database administrative region Oracle Names servers database store. The root administrative region contains its own details plus network addresses in subset (delegated) hierarchical administrative regions. Obviously the root administrative region will only contain Oracle Names server addresses for its own Oracle Names servers plus direct administrative region subset Oracle Names server addresses.

Oracle Names Server Configuration for Multiple Domains

Configuring Oracle Names Server

Oracle Names server environments can be implemented in one of two general configurations. Oracle Names server environments can have their data continuously replicated across all Oracle Names servers or have all region location Oracle Names servers store their data into a region specific database. If the database is ever unavailable cache'd data and cache'd configuration is used. Oracle Names server environments can also be divided into adminsitrative regions containing multiple Oracle Names servers with multiple domains. Multiple administrative regions must be contained within a single, centralised root administrative region.

All Oracle Names server configuration files are usually placed into $ORACLE_HOME/network/names. Cache information, data and configuration, is stored in various files.

Always create more than one Oracle Names server on a network using an Oracle Names server solution. If one Oracle Names server goes down another is available to take on all of the network load. A single Oracle Names server requires no configuration as a default. Configure an Oracle Names server database, creating specific Oracle Names server tables, by executing a script called $ORACLE_HOME/network/admin/names/namesini.sql under a newly created username / schema.

An Oracle Names server can be tested by executing the NAMESCTL utility PING command. This command can effectively ping multiple, space separated, Oracle Names server names.

Preferred Oracle Names Servers

In a network environment involving multiple Oracle Names servers certain Oracle Names can take precedence over (be preferred over) other Oracle Names servers. This is allowed because sometimes some Oracle Names server addresses in a network are faster response addresses than others, depending on numerous factors. The NAMESCTL utility command REORDER_NS creates a list of Oracle Names servers based on network availability where each Oracle Names server is ranked in order based on response time and obviously, availability. Is an Oracle Names server, machine, regional database, etc. up and running ? When setting preferred Oracle Names servers these preferred Oracle Names servers will allow a manual override of the automated Discover process of Oracle Names servers. The easiest way to set up preferred Oracle Names servers is by using the Net8 Assistant program or $ORACLE_HOME/bin/netasst.

Oracle Names Control Utility (NAMESCTL)

Oracle Names Server Parameters

Oracle Names server parameters are stored in the $ORACLE_HOME/network/admin/names.ora file.