Checking the Database (SAP Library - SAP Database Guide: Oracle (BC-DB-ORA-DBA))

Checking the Database

Use

You check the database when using SAPDBA to perform a partial restore and complete recovery of your Oracle database. This procedure checks the database for critical errors that might prevent production operation.

SAPDBA analyzes the appropriate V$ database tables to check:

Data files

Existence
Status: OK, RECOVERY

Status: ONLINE, OFFLINE

Tablespaces

Status: ONLINE, OFFLINE

Status: BEGIN BACKUP, END BACKUP

Control files

Existence
Validity if necessary

Online redo log files

Existence
Status: OK, STALE, DAMAGED

Note

These checks do not find out, for example, whether table indexes are missing. To do this, use the Oracle database monitor in the SAP System.

Since some of the V$ tables are only updated when the database is restarted, SAPDBA differentiates between the following:

Online quick check

This check is performed with the database open. However, you cannot then recover the database with SAPDBA because the information obtained from this check is not necessarily current. As a result, if you have only performed the online quick check, the Check database function is set to status not finished.

You can perform the online quick check at any time, in order to check the status of the control files, data files, and the online redo log files.

In addition, you can use the SAPDBA menu option Archive mode ® Show complete archive history to determine initially which redo log files are necessary for a recovery, starting from the last backup.

Offline safe check

This is a comprehensive check and is required if you want to later restore and recover the database. Before a safe check, SAPDBA switches the database offline then remounts it. This guarantees that the information in the V$ tables is up-to-date. When the offline safe check is finished, and as long as it resulted in no errors, the database is opened again.

Prerequisite

You want to check the database after a problem has occurred.

You have configured and started SAPDBA. Refer to Getting Started with SAPDBA.

The database can be either online or offline, but a safe check is only possible if the database is offline.

Procedure

Choose Restore/recovery ® Partial restore and complete recovery ® Check database in SAPDBA.

SAPDBA displays the restore and recovery options.

If required, change the restore and recovery options.

Enter y to continue.

SAPDBA checks the control files, data files, links, and bad entries in the control file, then asks whether you want to perform an offline safe check.

To perform a safe check, enter y.

If the database is online, SAPDBA warns you that the database will be shut down immediately for the safe check.

To shut down the database and continue with the safe check, enter y.

SAPDBA shuts down the database and comprehensively checks the database.

Result

SAPDBA reports any problems that it finds, such as a missing data file.

What happens at the end of the check depends on whether SAPDBA finds any errors:

If the check was successful (that is, there were no errors), SAPDBA reopens the database. It also sets the Status of the check in the menu to Finished and the Status of all subsequent steps to not allowed.

If errors are found, the database remains offline and SAPDBA does the following:

If defective data files are found, SAPDBA creates an internal list of the damaged files. Based on this list, SAPDBA determines how to restore and recover the database.

If the control files or redo log files are in a critical condition for the recovery, SAPDBA terminates the database check. You cannot solve this type of error with SAPDBA. You need to take appropriate action using Oracle tools. For more information, see the Oracle documentation and Recovery with SQLPLUS. Once you have removed the error, you can restart the database check.

To continue with the partial restore and complete recovery, perform Finding the Backup Files.