Oracle RAC Datafile Activity Test

This test indicates the level of read/write activity on each datafile in the shared cluster storage.

Target of the test : Oracle Cluster

Agent deploying the test : An internal agent

Outputs of the test : One set of results for every datafile in the shared cluster storage monitored.

Configurable parameters for the test
  1. TEST PERIOD - How often should the test be executed
  2. Host – The host for which the test is to be configured
  3. Port - The port on which the server is listening
  4. orasid - The variable name of the oracle instance
  5. 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 ServiceName of a cluster, execute the following query on any node in the target cluster:

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

  6. User – In order to monitor an Oracle RAC, a special database user account has to be User – 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.

  7. Password – Password of the specified database user
  8. Confirm password – Confirm the password by retyping it here.
  9. ISPASSIVE – If the value chosen is yes, then the Oracle server under consideration is a passive server in an Oracle cluster. No alerts will be generated if the server is not running. Measures will be reported as “Not applicable’ by the agent if the server is not up.
  10. show datafile path- This test reports a set of results for each datafile on the target Oracle database server. This means that every datafile is a descriptor of this test. By default, while displaying the descriptors of this test, the eG monitoring console does not prefix the datafile names with the full path to the datafiles. This is why, the show datafile path flag is set to No by default. If you want the data file names to be prefixed by the full path to the data files, then, set the show datafile path flag to Yes.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Physical block read rate:

Indicates the rate at which disk blocks are being read from this datafile.

Blocks/Sec

A scenario in which more than 50% of blocks are being read from a single datafile could signify a problem.

Physical block write rate:

Indicates the rate at which disk blocks are being written to this datafile.

Blocks/Sec

A scenario in which more than 50% of blocks are being written to a single datafile could signify a problem. Too much activity to a specific datafile can result in reduced database performance. To improve performance, consider balancing I/O across disks, and reorganize tables across tablespaces to reduce activity to a specific datafile.

Percent total I/O:

Indicates the percentage of total I/O operations on the database server that were handled by this data file.

 

Percent

Disk reads and writes are expensive operations and all I/Os should be balanced across the different data files of an Oracle database for optimal performance. This metric reports the percentage of all I/O of an Oracle database that are happening on each of the data files of the Oracle database. This metric allows an Oracle administrator to determine which is/are the hot data file(s) (e.g., which data file is handling 80% of the total I/O).