Database Reference
In-Depth Information
Configuring the RMAN environment
Recovery Manager options can either be configured globally or at runtime. Options supplied at runtime take
precedence over those defined globally. To view the configuration options, connect to the target database and catalog
and type the “show all” command as shown in Listing 11-1.
Listing 11-1.
Configuration options for Recovery Manager
RMAN> show all;
RMAN configuration parameters for database with db_unique_name CDB1 are:
CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 8 DAYS;
CONFIGURE BACKUP OPTIMIZATION OFF; # default
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE CONTROLFILE AUTOBACKUP ON; # default
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
CONFIGURE DEVICE TYPE DISK PARALLELISM 4 BACKUP TYPE TO BACKUPSET;
CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE MAXSETSIZE TO UNLIMITED; # default
CONFIGURE ENCRYPTION FOR DATABASE OFF; # default
CONFIGURE ENCRYPTION ALGORITHM 'AES128'; # default
CONFIGURE COMPRESSION ALGORITHM 'BASIC' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE ;
# default
CONFIGURE RMAN OUTPUT TO KEEP FOR 7 DAYS; # default
CONFIGURE ARCHIVELOG DELETION POLICY TO NONE; # default
CONFIGURE SNAPSHOT CONTROLFILE NAME TO
'/u01/app/oracle/product/12.1.0.1/dbhome_1/dbs/snapcf_CDB1.f'; # default
The following sections will explain the most important of these options.
Explaining the retention policy
The backup retention policy determines how backups are treated before they are considered obsolete by RMAN, and
therefore eligible for removal. The first option is to keep a number of backups to satisfy a time window for recovery.
The so-called recovery window is the window for which backups exist for a point in time recovery. A common case is
to keep a week's worth of backups available. The aim is to be able to perform point in time recoveries anytime between
the current time and seven days before that time. If your level 0 backup is created halfway in the 7 days—maybe at
day 3—then it will be necessary to keep a previous backup. Otherwise you would not be able to restore a database at
day 1. Although it is conceptually simple to understand a recovery window, it can become a headache to the backup
and storage administrators since it is impossible to predict the backup volume. If, for example you decide to take
additional backups from the backup strategy then the projected data volume increases proportionally to the number
of additional-read: unplanned-backups taken.
The use of a recovery window is not the default. To enable it you have to issue the following statement in RMAN:
RMAN> configure retention policy to RECOVERY WINDOW OF X DAYS;
Simply substitute X with the number of days you need. You should match the value of the database's
controlfile_record_keep_time
with the recovery window, or have the initialization parameter greater than the
RMAN policy.
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