Split Mirror Online Backup

Use

This section describes how you can use BRBACKUP to perform a split mirror online backup with your Oracle database. We especially recommend this for large databases where high availability is an important consideration.

In an online backup the system remains available the whole time. The tablespaces to be backed up are temporarily set to BACKUP status while the mirror disks are split. In comparison to the normal online backup, in which the tablespaces retain this status during the whole backup period, the amount of redo information is significantly reduced.

Prerequisites

You set the following parameters in the initialization profile init<DBSID>.sap:

?      backup_type:

0       Split command scenario: backup_type = online_split

0       SPLITINT scenario: backup_type = online_mirror

Instead of the backup_typeparameter, you can enter the BRBACKUP command option -t|-type as shown below in "Activities." The BRBACKUP command option takes priority.

?      Split command scenario: split_cmd and resync_cmd

?      SPLITINT scenario: split_options and split_resync

All copies of control files must be located on disks that can be split, for example, in sapdata directories.

Activities

Split Command Scenario

You start BRBACKUP on the backup host using the following command :

brbackup -t online_split

For more information, see -t|-type.

BRBACKUP then performs the following steps:

...

       1.      Sets the tablespaces to be backed up to backup status using:

ALTER TABLESPACE <tablespace name> BEGIN BACKUP;

       2.      Splits the mirror disks using split_cmd.

       3.      Resets the tablespaces to the normal status using:

ALTER TABLESPACE <tablespace name> END BACKUP;

       4.      Backs up the mirror disks on the backup host.

       5.      If you have set resync_cmd, synchronizes the mirror disks with the originals.

SPLITINT Scenario

You start BRBACKUP on the backup host using the following command :

brbackup -t online_mirror

For more information, see -t|-type.

BRBACKUP and SPLITINT then perform the following steps:

...

       1.      BRBACKUP calls SPLITINT without setting the tablespaces to backup status.

       2.      SPLITINT prepares the split. When complete, SPLITINT sends a message to BRBACKUP.

       3.      When BRBACKUP receives the message, it sets the tablespaces to backup status.

       4.      SPLITINT executes the split. When complete, SPLITINT sends a message to BRBACKUP.

       5.      When BRBACKUP receives the message, it takes the tablespaces out of backup status.

       6.      SPLITINT completes the split and sends a success message before returning control to BRBACKUP.

       7.      BRBACKUP starts the actual backup (for example, with BACKINT).

Resynchronization (the next step) occurs after the actual backup (for example, with BACKINT) has finished. It is optional and only needs to be executed if the setting in init<DBSID>.sap is split_resync = yes.

       8.      SPLITINT performs the resynchronization and sends a success message before returning control to BRBACKUP.

       9.      BRBACKUP cleans up and terminates.

For more information, see the documentation BC-BRI SPLITINT Interface for Oracle Databases, which you can find on SAP Service Marketplace at:

service.sap.com/dbaora  ®  Media Library  ® Backup and Recovery

See also:

Split Mirror Backup: Software Configuration