Backing Up Oracle Using Tivoli Storage Management

Chapter 6. Oracle backup considerations on UNIX 81

6.4 Backup examples

This section describes some typical backup examples using RMAN, complete

with sample scripts. The examples are based on the following database

instances:

• Target database

: paris

• Recovery catalog database:

rio

For the examples, we used RMAN command files and redirected the output to

logfiles. RMAN command files are regular text files containing commands

executed by RMAN.

The examples illustrate how to perform the following functions:

• Consistent whole database backup

• Archive redo log backup

• Incremental level 0 backup

6.4.1 Consistent whole database backup

In the following examples, we are using RMAN to shut down and restart the

database, to guarantee that all read-write datafiles and control files have

been check-pointed with respect to the same system change number (SCN).

These examples are suitable for databases operating in ARCHIVELOG and

NOARCHIVELOG mode, and in our opinion, they represent the most

common backup operation:

rman target internal/manager@PARIS rcvcat rman/rman@RIO

cmdfile=backup_offline_paris log=backup_offline_paris.log

82 Backing Up Oracle using Tivoli Storage Management

Figure 17. Whole consistent backup, commandfile backup_offline_paris

To guarantee that a database’s datafiles are consistent, shut down the

database with the NORMAL, IMMEDIATE or TRANSACTIONAL options

before making a whole database backup. To bring up the database in the

desired state, we chose the sequence:

•

shutdown immediate;

•

startup force dba;

•

shutdown immediate;

•

startup mount;

For TDP for Oracle environment variables in the

allocate channel command:

• DSMO_NODE is set because we use a different node name to the TSM

backup client.

• DSMO_AVG_SIZE is a size estimate used by the TSM server to reserve

space on TSM storage.

• DSMI_ORC_CONFIG points to our dsm.opt file.

• DSMI_LOG points to our backup log directory - the default is the

$ORACLE_HOME/dbs directory of the Oracle instance PARIS.

• The allocation of multiple channels is only possible when TSM node’s

MAXNUMMP (maximum mount points allowed) is greater than or equal to

the number of channels.

Chapter 6. Oracle backup considerations on UNIX 83

The following is an explanation of various statements in our coding example:

•

set maxcorrupt for datafile 1 to 0 causes Oracle to abort the backup

process if RMAN detects corrupt blocks in the SYSTEM tablespace.

In our database, we used AUTOEXTEND=ON for all datafiles. Datafile 1 is

always used for the SYSTEM tablespace.

•

backup full causes a whole database backup.

•

filesperset 3 forces RMAN to include maximal 3 files in a backup set.

A possible restore from a single datafile will be processed faster.

•

format ‘%d%t%s%p’ creates a TSM low level name including database

name/timestamp/backup set number/backup piece number

•

tag ‘paris offline 20010316.1111’ is a user defined symbolic name which

is assigned to backup sets. It makes it easier to address these backups in

RMAN restore or change commands.

•

alter database open finally makes the database accessible to users.

6.4.2 Archived redo log backup

The next examples show how to back up archived redo logs.

In both examples, the current log is archived before the backup archivelog is

started.

The first example uses only one log archive destination as input for the RMAN

backup and two different channels to speed up the process.

With the

filesperset 20 RMAN creates up to 20 backup pieces in one backup

set.

The

delete input option tells RMAN to deletes the archive logs on disk after a

successful backup:

84 Backing Up Oracle using Tivoli Storage Management

.

The second archivelog backup example is more complex — but also more

safe. Assume that a very important database is configured in the following

way:

• Oracle uses multiple log groups

• Each group contains multiple log members

• At least two log archive destinations are in use

Because the

backup archivelog all command backs up exactly one copy of

each distinct log sequence number, RMAN does not put two copies of the

same log sequence number into the same backup set. Furthermore, if you

specify the

delete input option, RMAN only deletes the specific copy of the

archived redo log that it backs up.

The easiest solution in this case is to back up both copies of each archived

redo log and then delete both copies. Use the

like pathname parameter to

indicate which destination to use. The

like parameter allows you to match

filenames in both archive destinations.

Chapter 6. Oracle backup considerations on UNIX 85

Refer to Figure 18 for a diagram of this complex situation.

Figure 18. Multiple log groups, archive log destinations, different tape drives in TSM