Configuring Oracle SNMP Support
T his chapter provides an overview of the Oracle SNMP Support feature, available with Oracle7 Server release 7.2 and SQL*Net release 2.2 and later. Oracle SNMP Support enables Oracle products running anywhere on an enterprise's network to be located, identified, and monitored by a management station running at one or more centrally located nodes.
This chapter briefly describes the tasks necessary to configure Oracle SNMP Support for the Oracle7 Server, Listener, MultiProtocol Interchange, and Oracle Names. For specifics on how to configure SNMP support, see Oracle Network Manager Administrator's Guide. For specific instructions on how to install and configure SNMP support on a particular platform see your operating system-specific documentation.
For a complete description of SNMP concepts and terms, see the Oracle SNMP Support Reference Guide. It provides detailed listings of what the management information contains and suggestions on how to use it effectively in developing SNMP-based management applications.
What is the Purpose of SNMP?
The Simple Network Management Protocol (SNMP) was designed for the purpose of querying and transferring management information between nodes on a network. As a protocol, SNMP defines how information is conveyed between "managed" nodes and "managing" nodes on an enterprise's network. In the past, managed nodes have included network devices such as bridges, routers, hubs, network interface cards, network monitors, and analyzers. However, the set of managed network objects is evolving to include software applications in addition to network devices. The managing nodes consist of workstations at which any one of a number of system and network management applications are run. These programs, based upon SNMP, are variously called network management platforms or frameworks.
For a discussion of terms, concepts, and principal components related to SNMP, such as network management station ("manager nodes"), managed nodes or elements, Management Information Base (MIB), and SNMP Master Agent and subagent, refer to the Oracle SNMP Support Reference Guide.
Oracle SNMP Support for Oracle Services
Oracle SNMP Support is a bundled feature of SQL*Net release 2.2. SNMP is a standard underlying many popular network management systems.
Oracle SNMP support allows an Oracle7 Server, listener, MultiProtocol Interchange, or Oracle Names Server to be queried by any SNMP-based network management system such as Hewlett-Packard's OpenView, IBM's NetView6000, and DEC's POLYCENTER/NetView. SNMP support is built into the SQL*Net listener, Oracle Names, and MultiProtocol Interchange--it is not a separate executable. For example, when a network listener, Oracle Names Server, or MultiProtocol Interchange is started, SNMP support is automatically started. The SNMP Master Agent must be running before starting any subagent. For information on starting the SNMP Master Agent refer to your operating system-specific documentation.
The SNMP subagent for the Oracle7 Server is a separate executable, and must be started separately. For information see "Controlling theOracle Database Subagent" later in this chapter.
Benefits of Oracle SNMP Support
Oracle SNMP support allows a network listener, Oracle7 database, Oracle Names Server, and MultiProtocol Interchange to be queried by any SNMP-based network management system. The primary benefits of Oracle SNMP Support are:
- Oracle products can be located, identified, and monitored in realtime across enterprise networks of any size.
- Database administrators see the current status of Oracle products, selecting from among several status variables that are defined for each product in a management information base (MIB).
By using a management framework such as HP's OpenView, DBAs can see at a glance how the Oracle environment is running. Among the tasks that Oracle SNMP Support allows DBAs or network administrators to do are to:
- monitor the status of Oracle services such as databases or tools throughout the network
- identify performance bottlenecks
- "discover" Oracle databases or tools as they start up on any node
- receive alerts when exceptional events occur, for instance, the database going down
- define thresholds and automatic responses to specific events
- detect and diagnose potential problems quickly and easily
- be notified when certain events occur
- store, report upon, filter, and analyze historical data
Installing and Configuring Oracle SNMP Support
This section briefly describes the major tasks that the network administrator must perform to enable SNMP support for an Oracle network service.
Consider Hardware and Software Requirements
There are certain hardware and software requirements that need to be met. See your platform-specific documentation for more information.
Installing Oracle SNMP Support
Oracle SNMP Support is installed with the Installer. For information on how to install the product on your platform refer to the operating system-specific documentation.
Configuring SNMP Support
Following are some general tasks the network administrator needs to perform to configure SNMP support on a managed node:
Note: The actual file locations and utilities may vary from platform to platform.
1. Configure the SNMP Master Agent. Refer to your operating system-specific documentation for instructions.
2. Configure the subagent for the Oracle7 server, listener, MultiProtocol Interchange, and Oracle Names network services using the SNMP pages in Network Manager.
To configure an SNMP subagent, you configure between three and five of the following parameters on the Database SNMP, Listener SNMP, Names Server SNMP, and MultiProtocol SNMP Pages:
- Username--optional (specified for an Oracle database server only)
- Password--optional (specified for an Oracle database server only)
Attention: Make sure that you assign each visible service a unique index number.
3. Run the CATSNMP.SQL script to create the new user, role, and grants required by Oracle SNMP Support in all databases visible over SNMP.
If you change the default username and password with the CATSNMP.SQL script, you must also specify the new username and password in the SNMP page of Network Manager.
Using Oracle SNMP Support
Following are things you must do before using Oracle SNMP Support:
Start the Master Agent, Encapsulator, and Native SNMP Agent
This varies depending on the platform. See your operating system-specific documentation for the actual command names and instructions.
Controlling the Oracle Database Subagent
The SNMP subagent is a separate executable from the database, and it is not started automatically when the database is started.
To start, stop, and check to see if the database subagent is running or not, use the following commands from LSNRCTL:
LSNRCTL> dbsnmp_start
LSNRCTL> dbsnmp_stop
LSNRCTL> dbsnmp_status
You must run these commands on the machine where the SNMP subagent is running--there is no remote support.
Attention: The Master Agent must be running before starting the subagent.
Controlling SNMP Support for Network Services
The subagents for the listener, MultiProtocol Interchange, and Oracle Names Server are started when the listener, MultiProtocol Interchange, are Oracle Names Server are started. They are not separate executables, as with SNMP support for the Oracle database.
Polling Database MIB Variables
In using, tuning, and understanding applications that poll the SNMP-managed applications, some skill is required in taking the proper measurements at the proper times, accurately interpreting the data, and making sure that the very act of managing a process does not impose undue performance demands on that process.
Attention: Measuring performance should not negatively impact the performance.
As inherent components of the applications, the subagents for the listener, Interchange and Oracle Names always have access to the current value for any MIB variable. However, as a separate process from the database, there is some cost associated with the database subagent's querying a value. To reduce the impact of its queries against the database, the database subagent maintains a cache of values that it has retrieved from the database. The length of time that each variable is considered "fresh" may have one of two values: FAST or SLOW.
All variables retrieved by the database subagent, whether in the standard or Oracle Database MIB, are labeled as either FAST or SLOW. Only variables in the two database MIBs have this classification. Networking product subagents have access to internal data structures that are updated continuously; they do not cache values like the database Agent.
Polling Intervals
The polling times are hardcoded and cannot be configured. If polling times could be configured, problems in developing applications would result. Graphical elements would exhibit a false value, depending upon the frequency of polling and cache intervals. If various machines and services on a network had different polling intervals, significant problems might result.
FAST Variables
FAST variables are retrieved every 30 seconds or more. If a new query comes in and the subagent sees that the cached value is less than 30 seconds, it returns that value AGAIN. If the cached value is older than 30 seconds, it obtains the new value and returns it, as well as caches the new value.
SLOW Variables
SLOW variables are retrieved once every 5 minutes or more.
