Databases Reference
In-Depth Information
Oracle Corporation recently entered the circle of companies that provide media manage-
ment software by offering Oracle Secure Backup (see
Oracle Secure Backup Administrator's
Guide
). Other well known players are Hewlett Packard with OmniBack, Symantec with NetBackup
and Tivoli Software with Tivoli Storage Manager.
DBMS_BACKUP_RESTORE
makes extensive use of the control file to keep track of what was
backed up, when, and how. Here,
when
means at what time the backup started and when it
ended.
What
means what type of file, such as control file, data file, or archived redo log file.
How
refers to the medium that holds the backup, such as a file system mounted on the data-
base server or a media manager as well as the incremental level at which the backup was taken.
Note that Oracle10
g
only supports incremental levels 0 and 1, whereas Oracle9
i
and previous
releases supported levels 0 to 4. Considering that there are cumulative backups on top of the
default differential backups, there is no truly compelling argument for more than two levels.
In what follows, the data inside the control file representing the
when
,
what
, and
how
will
be called backup metadata. Please refer to Table 17-1 for an overview of some of the V$ views
that provide access to the metadata.
Table 17-1.
Backup-Related V$ Views
V$ View
Purpose
Related RMAN
Command
V$ARCHIVED_LOG
BACKUP
ARCHIVELOG
Archived redo log files, their thread
number, sequence number, and status
(available, deleted, expired, or unavailable)
DELETE
ARCHIVELOG
CATALOG
ARCHIVELOG
V$BACKUP_DATAFILE
Backups of data files (
FILE#
>
0
) and
control files (
CONTROLFILE_TYPE
IS
NOT
NULL
); both types of files may be present
in the same backup piece since a backup
of file 1, which belongs to tablespace
SYSTEM, also backs up the control file,
unless automatic control file backups are
enabled (
AUTOBACKUP
)
BACKUP
DATABASE
BACKUP
TABLESPACE
BACKUP
DATAFILE
BACKUP
CURRENT
CONTROLFILE
V$BACKUP_PIECE
BACKUP
Backup pieces with creation time,
device type, status, and path name
(column
HANDLE
)
V$BACKUP_SET
BACKUP
Backup sets consist of one or more
backup pieces, in case the files
contained in a backup set exceed
the maximum piece size
V$BACKUP_SPFILE
BACKUP
SPFILE
Backups of the server parameter file
V$BACKUP_REDOLOG
BACKUP
ARCHIVELOG
Backups of archived redo logs
