Types of Database Errors

There are a number of errors that hinder the operations of an Oracle database or can cause the database to crash. Depending on the type of error, a recovery can either be carried out automatically or must be performed by the user or database administrator.

It is therefore important for you to find out the exact type of error before intervening in any way, to be able to act correctly and adequately.

Errors can generally be divided into five categories:

• User errors, see
Recovery after User Errors

• Statement errors, see
Recovery after Statement Errors

• Process errors, see
Recovery after Process Errors

• Instance errors, see
Recovery after an Instance Error

• Media errors, see
Recovery after Media Errors

SAPDBA: Check (and Repair) Database

Different types of errors can interfere with the operation of an ORACLE database recovery.

The task of the SAPDBA recovery function is to remedy certain media and user errors. When such an error occurs, it usually involves the loss of database files, which can contain many different types of objects: ORACLE Dictionary segments, temporary segments, rollback segments, or user segments (tables and indexes).

SAPDBA supports restoring the database after the loss of the following files:

• Data files of the SAP tablespaces (PSAPD/I)

• Files of the system tablespace (SYSTEM)

• Files of the rollback tablespace (PSAPROLL)

• Files of the temporary tablespace (PSAPTEMP)

The menu item Check (and repair) database only enables recovery of the database up to the current time. If you want to restore an older version of the database or perform a point in time recovery, please use the Restore/Recovery function (

SAPDBA Support for Raw Device Configuration

The following information is important for you if you intend to use SAPDBA for ORACLE database administration on raw devices:

• The data for a tablespace can be stored either in raw devices or in files. Be sure to observe the SAP naming convention for tablespaces on raw devices:

/sapraw/_ ® /

: Sequence number assigned to the raw devices (or files) belonging to the tablespace

: Specifies the central directory containing the devices. This directory may also be specified in the rawdev_dir parameter.

: _

See also Environment Variables.

Each tablespace "file" (held on a raw device) visible to ORACLE is a symbolic link to a raw device. SAPDBA checks that the naming convention has been observed.

Tablespace PSAPDOCUD

/oracle/C11/sapraw/docud_1 ® /dev/rdsk/C11docud_1

You should also compare this with the Naming Convention for tablespaces in the file system.

• The database link structure is one of things recorded in the structure log
struct.log.

If the database check is done using SAPDBA, SAPDBA uses this structure log to check whether the link structure is still complete and immediately repairs it if not. If a tablespace is extended, a new tablespace is created or a tablespace is reorganized with data files then SAPDBA updates the structure log. See Structure Log.

• Each raw device can contain only one tablespace "file" (requirement of ORACLE). SAPDBA can set the size of this partition. Therefore, in the case of tablespace extension (adding a "file" from a raw device), for example, the size of the raw device is determined automatically and is used for the size of the file. See
Extending a Tablespace.

• It may be a good idea to specify the
rawdev_dir and blkdev_dir parameters in the init.dba profile.