eG Monitoring
 

Measures reported by OraCrptBlkTest

A data block is corrupted when it is not in a recognized Oracle Database format, or its contents are not internally consistent. Block corruptions may affect only a single block or a large portion of the database. It is hence important to rapidly isolate and eliminate corrupted blocks.

Using this test, you can not only identify how many blocks are corrupted in your database, but can also determine which blocks have been corrupted.

The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
Unique_file_count Indicates the number of corrupted blocks in this Oracle database. Number Ideally, the value of this measure should be zero. A high value indicates that too many blocks in the database are corrupted. If allowed to grow, it could affect the whole database, causing significant loss of data.

The first step towards correcting corruption therefore is know where the corruption has occurred and understand the nature of the corruption. Towards this end, eG Enterprise offers the detailed diagnosis capability. By enabling this capability for this test, you can view the details of corrupted blocks such as the exact file number, file name, block number where the corruption starts, number of corrupted blocks, corruption change and the corruption type.

Once the corrupted objects are identified, you can use one of the many methods that Oracle provides for rectifying the corruption. One method of correction is to drop and re-create an object after the corruption is detected. However, this is not always possible or desirable. If data block corruption is limited to a subset of rows, another option is to rebuild the table by selecting all data except for the corrupt rows.

Yet another way to manage data block corruption is to use the DBMS_REPAIR package. You can use DBMS_REPAIR to detect and repair corrupt blocks in tables and indexes. Using this approach, you can address corruptions where possible, and also continue to use objects while you attempt to rebuild or repair them.