学步园

·how databases store their data
·how data backups from SAP system can be performed
Objectives
at the conclusion of this unit, you'll be able to:
·back up the database
·determine whether your database backups have been successfully performed
ADM 100 mySAP Technology Admin (p107)

 DBA Planning Calendar 

 Backup Media 

You can display and configure the backup media.

Prerequisite

Prerequisites

Procedure

·        User menu Configuration
In the user menu, choose Database: Monitoring ® Database Assistant (transaction DB50).
Choose Configuration ® Backup Media.

·        DBA Planning Calendar
Open the DBA Planning Calendar (transaction DB13 or DB13C).
Choose Backup Media.

Choose Edit ® Media Group or Edit ® Create Medium, and create a group of parallel backup media or a single backup medium.
Choose Edit ® Properties when you want to change the specifications of a backup medium.

 Data Backup 

 Complete Data Backup 

In a complete data backup, all the pages of the data volumes are backed up to the backup medium you specified.

 Incremental Data Backup 

In an incremental data backup, all the pages of the data volumes changed since the last complete data backup are backed up to the backup medium you specified

 Scheduling Concept 

To ensure the secure operation of your database system, you have to create a scheduling concept for the following database activities:

·        Data backups

·        Log backups

·        Updating statistics of the SQL Optimizer

·        Checking the Database Structures

You can schedule, start, and monitor these activities with the DBA Planning Calendar. You can use external backup tools to increase the speed of the backup.

Data Backups

Note that in the case of a recovery, the more up-to-date that the last backup is, the fewer log entries have to be reloaded. Therefore, perform data backups as often as possible.

·        Perform at least one complete data backup (complete data backup) every week (at the weekend, if possible).

·        On each day that the database is productive, start an incremental data backup.

If a complete data backup is active you cannot start an incremental data backup.

You can perform data backups in parallel to increase the speed of each backup.

Follow the procedure described in Scheduling a Data Backup.

Log Backups

In production systems, make sure that your log settings include the following: hardware-based mirroring of the log area, the log area can be overwritten only once it has been backed up, and redo log management must always be activated. Perform log backups regularly.

·        Automatic Log Backup

The automatic log backup (autosave log mechanism) must always be activated (see Activating the Automatic Log Backup). Complete and incremental data backups are also possible while the automatic log backup is activated.

Check regularly that automatic log backups are activated. To do this, see the Log Area State in the DBA action log display.

·        Interactive Log Backup

If automatic log backups are deactivated, you have to check regularly that there is enough memory space is available in the log area (see Checking the Available Log Memory Space). If no new log entries can be written due to lack of memory space in the log area, the database system shuts down. If necessary, save the log area immediately by starting an interactive log backup (see Scheduling a Log Backup).

·        Archiving the Version Files

Regularly archive the version files that are written during a log backup on a medium of your choice. After these files have been archived successfully, you can delete the version files that were written during the log backup. This ensures that there is always enough space in the directory for the version files.

If you use an external backup tool, you can automate the process for archiving version files. To do this, proceed as described in Archiving the Version Files of the Log Area.

You cannot schedule the archiving of the version files in the DBA Planning Calendar.

Make sure that tapes that contain data or log backups are not overwritten the next time that you perform a backup. By keeping the last four backup generations, for example, you still have the option of using an older backup if an error occurs on a particular medium.

Updating the SQL Optimizer Statistics

Execute the function create new optimizer/space statistics once after an installation, upgrade, or database migration.

Subsequently, you need to update the statistics only once a week (if possible at the weekend). To do this, use the functions check optimizer statistics and refresh optimizer/space statistics (Scheduling Updates for SQL Optimizer Statistics).

Database Structure Checks

You must check the database structures at the latest before the backup media in a backup cycle are overwritten again. The following recommendations are based on a backup cycle of 4 weeks.

Every four weeks (if possible on a weekend), check the database structures for all database objects (tables and indices). To do this, use the function check database structure (all objects). This structure check may take some time, depending on the size of your dataset.

Alternatively, or additionally, you can check the database structures for all tables. To do this, use the function check database structure (only tables). Indices contain redundant information and can be restored after errors. Therefore, you do not need to check their structures as regularly.

To schedule database structure checks, proceed as described in Scheduling a Database Structure Check.

You can check structures for a single table by means of the user menu Tables/Views.

Result

Check regularly whether the scheduling concept meets your security requirements for the database system. To do this, you can use the option of generating a recovery report (display in DBA action logs).