Oracle RAC Dataguard Status Test

Oracle Cluster Database lets you save filled groups of redo log files to one or more offline destinations, known collectively as the archived redo log, or more simply the archive log. The process of turning redo log files into archived redo log files is called archiving. Data Guard manages the transmission of redo data using the Redo transport services.

Redo transport services control the automated transfer of redo data from the production database to one or more archival destinations.

Redo transport services perform the following tasks:

  • Transmit redo data from the primary system to the standby systems in the configuration
  • Manage the process of resolving any gaps in the archived redo log files due to a network failure
  • Enforce the database protection modes
  • Automatically detect missing or corrupted archived redo log files on a standby system and automatically retrieve replacement archived redo log files from the primary database or another standby database.

There are several types of destinations supported by redo transport services. They are:

  • Oracle Data Guard standby databases
  • Archived redo log repository
  • Oracle Streams real-time downstream capture database
  • Oracle Change Data Capture staging database

If the destination at which the redo logs have to be archived is not available, then there would be a considerable difference in the data stored between the production database and the standby databases within an Oracle Cluster. To avoid such indifferences and maintain proper synchronization of data, it is essential to monitor the status of the destination at which the log files are archived constantly. The Oracle RAC Dataguard Status test helps administrators in this regard!

For each destination at which the redo logs are to be archived in a database instance, this test reports the current status of the destination and the current applied mode of the destination.

Target of the test : An Oracle Cluster database server on which Data Guard feature is enabled

Agent deploying the test : An internal/external agent

Outputs of the test : One set of results for each Oracle database instance: destination to which the redo log files are to be archived from the target Oracle Cluster Database server being monitored.

Configurable parameters for the test
Parameter Description

Test period

How often should the test be executed

Host

The host for which the test is to be configured.

Port

The port on which the server is listening.

Service Name

A ServiceName exists for the entire Oracle RAC system. When clients connect to an Oracle cluster using the ServiceName, then the cluster routes the request to any available database instance in the cluster. By default, the Service Name is set to none. In this case, the test connects to the cluster using the ORASID and pulls out the metrics from that database instance which corresponds to that ORASID. If a valid service name is specified instead, then, the test will connect to the cluster using that Service Name, and will be able to pull out metrics from any available database instance in the cluster.

To know the Service Name of a cluster, execute the following query on any node in the target cluster:

select name, value from v$parameter where name =’service_names’

ORASID

The variable name of the oracle instance.

Username

In order to monitor an Oracle database server, a special database user account has to be created in every Oracle database instance that requires monitoring. A Click here hyperlink is available in the test configuration page, using which a new oracle database user can be created. Alternatively, you can manually create the special database user. When doing so, ensure that this user is vested with the select_catalog_role and create session privileges.

The sample script we recommend for user creation (in Oracle database server versions before 12c) for eG monitoring is:

create user oraeg identified by oraeg

create role oratest;

grant create session to oratest;

grant select_catalog_role to oratest;

grant oratest to oraeg;

The sample script we recommend for user creation (in Oracle database server 12c) for eG monitoring is:

alter session set container=<Oracle_service_name>;

create user <user_name>identified by <user_password> container=current default tablespace <name_of_default_tablespace> temporary tablespace <name_of_temporary_tablespace>;

Grant create session to <user_name>;                                

Grant select_catalog_role to <user_name>;

The name of this user has to be specified here.

Password

Specify the password of the specified database user.

Confirm Password

Confirm the Password by retyping it here.

Detailed Diagnosis

To make diagnosis more efficient and accurate, the eG Enterprise embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option.

The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled:

  • The eG manager license should allow the detailed diagnosis capability
  • Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Status

Indicates the current status of this archived redo log destination.

 

The values reported by this measure and its numeric equivalents are mentioned in the table below:

Measure Value Numeric Value
Valid 0
Alternate 1
Deferred 2
Full 3
Error 4
Disabled 5
Bad param 6

Note:

By default, this measure reports the current status of each archived redo log destination. The graph of this measure however, is represented using the numeric equivalents only - 0 to 5.

Recovery mode

Indicates the current applied mode on this archived redo log destination.

 

The values reported by this measure and its numeric equivalents are mentioned in the table below:

Measure Value Numeric Value
Managed 0
Managed real time apply 1
Logical real time apply 2
Logical apply 3
Idle 4

Note:

By default, this measure reports the current applied mode of the archived redo log destination. The graph of this measure however, is represented using the numeric equivalents only - 0 to 4.