How to Set Alert Thresholds-优快云博客

本文详细介绍了如何为数据库表空间设置警告和关键阈值，包括如何使用Enterprise Manager和DBMS_SERVER_ALERT来配置本地管理和字典管理表空间的警报阈值。还提供了将表空间警报阈值恢复到数据库默认值的方法，并解释了如何修改和查看警报。

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Setting Alert Thresh olds

For each tablespace, you can set just percent-full thresholds, just free-space-remaining thresholds, or both types of thresholds simultaneously. Setting either type of threshold to zero disables it.

The ideal setting for the warning threshold is one that issues an alert early enough for you to resolve the problem before it becomes critical. The critical threshold should be one that issues an alert still early enough so that you can take immediate action to avoid loss of service.

To set alert threshold values:

For locally managed tablespaces, use Enterprise Manager (see Oracle Database 2 Day DBA for instructions) or the DBMS_SERVER_ALERT.SET_THRESHOLD package procedure (see Oracle Database PL/SQL Packages and Types Reference for usage details).
For dictionary managed tablespaces, use Enterprise Manager. See Oracle Database 2 Day DBA for instructions.

Example—Locally Managed Tablespace

The following example sets the free-space-remaining thresholds in the USERS tablespace to 10 MB (warning) and 2 MB (critical), and disables the percent-full thresholds.

Note:

When setting non-zero values for percent-full thresholds, use the greater-than-or-equal-to operator, OPERATOR_GE.

Restoring a Tablespace to Database Default Thresholds

After explicitly setting values for locally managed tablespace alert thresholds, you can cause the values to revert to the database defaults by setting them to NULL with DBMS_SERVER_ALERT.SET_THRESHOLD.

Modifying Database Default Thresholds

To modify database default thresholds for locally managed tablespaces, invoke DBMS_SERVER_ALERT.SET_THRESHOLD as shown in the previous example, but set object_name to NULL. All tablespaces that use the database default are then switched to the new default.

Viewing A lerts

You view alerts by accessing the home page of Enterprise Manager Database Control.

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You can also view alerts for locally managed tablespaces with the DBA_OUTSTANDING_ALERTS view. See "Viewing Alert Data" for more information.

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Limitations

Threshold-based alerts have the following limitations:

Alerts are not issued for locally managed tablespaces that are offline or in read-only mode. However, the database reactivates the alert system for such tablespaces after they become read/write or available.
When you take a tablespace offline or put it in read-only mode, you should disable the alerts for the tablespace by setting the thresholds to zero. You can then reenable the alerts by resetting the thresholds when the tablespace is once again online and in read/write mode.