Automatic Backup in Oracle Database

Transcription

1 Automatic Backup in Oracle Database Miloš SÝKORA Slovak University of Technology Faculty of Informatics and Information Technologies Ilkovičova 3, Bratislava, Slovakia Abstract. One of the Database Administrator s (DBA) most important responsibilities is to keep the database available for use. To protect the data from all types of failures that can occur, the DBA must make regular backup of the database. In this paper I concentrate on the logical backup and cold (or offline) backup (database in NOARCHIVE LOG mode). Final product (set of scripts) will do the logical and cold backup of the Oracle database with selected frequency and send a log-file with results by to Database Administrator automatically. 1 Introduction Without a backup it is impossible for the DBA to get a database up and running, if there is a file loss, without loosing data. Backups are critical for recovering from different types of failures. Backup and recovery strategy depend on the type of company. For example I choose software Development Company, which needs the logical backup and cold (offline) backup of the testing database. 2 Backup scripts 2.1 Backup and Recovery strategy The nature of backups and recovery strategy is always affected by the type of business operations. In this case, I want to select proper backup and recovery strategy for the small Development Company. Supervisor: prof. Ing. Vladimír Vojtek, PhD., Institute of Applied Informatics, Faculty of Informatics and Information Technologies STU in Bratislava M. Bieliková (Ed.), IIT.SRC 2005, April 27, 2005, pp

2 146 Miloš Sýkora 2.2 Cold (offline) backup Database can be configured in Archivelog Mode, so that a history of the redo information is maintained in archived files, allowing for a complete recovery up to the point of failure. This option is suitable for situation where a database must be available 24 hours a day, 7 days a week for continuous option. Fig. 1. Backup Methods Development Company does not need this solution. Therefore, the database is configured in noarchivelog mode. The main feature of running database in noarchivelog mode is that the redo log files are used in a circular fashion. DBA may perform only operating system backups of the database when the database is shut down. During each backup must DBA backup the entire set of data files, redo log files and control files. In the case of failure DBA must recover these files from an earlier copy of a full database (offline backup). A closed database (cold) backup is an operating system backup of all data files, control files, redo log files, parameter files, and the password file that constitute an Oracle database. I define an operating system backup procedure that will always back up all necessary files as part of a strategy to safeguard against potential media failures that can damage files. It is a simple script that shut down the database, copies the data files, and opens the database. Then another script sends log file with results by to DBA. For a Development Company I select to perform cold backup twice a month.

3 Automatic Backup in Oracle Database 147 Fig. 2. Closed Database Backup Performing a closed database backup: 1. define local variables (ORACLE_HOME, ORACLE_SID DFILE) 2. connect to database 3. start spooling in log file 4. select start date 5. shutdown database 6. copy and pack all necessary files 7. startup database 8. select end date 9. stop spooling 10. send log file via to DBA 2.3 Logical backup Logical backup provides Oracle Export and Import Utility. Export utility provides a logical backup of database objects or an entire database. The import utility is used to read a valid Export file for moving data into database. For a Development Company I choose everyday logical backup in Full database mode. This mode exports all objects, except those in SYS schema.

4 148 Miloš Sýkora Fig. 3. Logical backup in Full database mode Performing a logical backup: 1. define local variables (ORACLE_HOME, ORACLE_SID DFILE, DATEF) 2. create directory for actual month (if necessary) 3. backup in Full database mode 4. pack Export file 5. send log file via to DBA 2.4 notification In previous sections I describe how to make backups. It is important to know for each DBA what the result of these scripts was. The easiest way is send an with the log file of screen output. Sending mails from operating system depends on platform. Because of this, DBA needs to implement the functionality of sending directly from the Oracle database. Oracle has an server option that allows programmer to send mail from within his code. In the case, users can send s to competent persons when a critical parameter is altered, when a database has some issues (for DBAs), or when a backup is over and so on. For s without attachment UTL_SMTP and UTL_TCP packages are required. UTL_SMTP is designed for sending over Simple Mail Transfer Protocol (SMTP). The UTL_TCP package provides TCP/IP client-side access functionality in PL/SQL.

5 Automatic Backup in Oracle Database 149 In this case DBA need to attach log files. When DBA sends using Java Stored Procedures (JSP) and the Sun Microsystems JavaMail package, attachments can also be sent. Performing mail notification: 1. Create the mail user 2. Grant appropriate role privileges to the mail user 3. Grant java permissions 4. Create java source 2.5 Installation The DBA have to ensure the complete path names of the files are noted and used appropriately in backup. In a multiple database environment, care must be taken to associate these files with the corresponding database through some naming convention, since the names of the parameter files and password files are not recorded in the database dictionary. Location of backup scripts depends on operating system platform. UNIX cron jobs can be scheduled with the crontab command. Windows can schedule any application using the Windows Scheduler. 3 Conclusions The primary goal of these backup scripts is to relieve the DBA from backup routine. Only what he has to do is check his s, and makes appropriate action (copy backup files to tape, etc). References 1. Schwinn, U., Venkatachalam, V.: Oracle8: Database Administration, Vol 1, (March 1998) 2. DiIanmi, J., Raman, S., Robson, P.: Oracle8: Backup and Recovery Workshop, Vol 1 (October 1998)