ALLOCATE CHANNEL FOR MAINTENANCE 命令

ALLOCATE CHANNEL FOR MAINTENANCE

Syntax

allocateForMaint::=

Text description of allocateForMaint

Purpose

To manually allocate a channel in preparation for issuing a CHANGE, DELETE,or CROSSCHECK command. Note that if you use CONFIGURE to set up automatic channels, then RMAN can use these automatic channels for maintenance operations; you do not have to manually allocate them.

If RMAN allocates the automatic maintenance channel for you, then it uses the same naming convention as any other automatically allocated channel. If you explicitly invoke ALLOCATE CHANNEL FOR MAINTENANCE, then RMAN uses the following convention for channel naming: ORA_MAINT_devicetype_n, where devicetype refers to DISK or sbt and n refers to the channel number. For example, RMAN uses these names for two manually allocated disk channels:

ORA_MAINT_DISK_1
ORA_MAINT_DISK_2

You can allocate multiple maintenance channels for a single job, but you should only use this feature in these scenarios:

• To allow crosschecking or deletion of all backup pieces or proxy copies, both on disk and tape, with a single command
• To make crosschecking and deleting work correctly in an Oracle Real Application Clusters configuration in which each backup piece or proxy copy exists only on one node

  See Also: Oracle Database Backup and Recovery Advanced User's Guide to learn how to crosscheck and delete on multiple channels

Restrictions and Usage Notes

• Execute this command only at the RMAN prompt. This command cannot be used within a RUN block.
• The target instance must be started.
• Do not specify a channel ID.
• You cannot allocate a maintenance channel to a shared session.
• You cannot prefix ORA_ to a channel name. RMAN reserves channel names beginning with the ORA_ prefix for its own use.
• Manually allocated and automatic channels are never mixed. To perform. maintenance on both disk and SBT simultaneously using manually allocated maintenance channels, you must allocate both channels explicitly.

Keywords and Parameters

Syntax Element	Description
DEVICE TYPE = deviceSpecifier	Specifies the type of storage device. See Also: "deviceSpecifier" Note: If you do not specify the DEVICE TYPE parameter, then you must specify the NAME parameter to identify a particular sequential I/O device. Query the V$BACKUP_DEVICE view for information about available device types and names.
allocOperandList	Specifies control options for the allocated channel. See Also: "allocOperandList"

Examples

Deleting a Backup Set: Example

This example deletes backup sets from tape created more than a week ago:

ALLOCATE CHANNEL FOR MAINTENANCE DEVICE TYPE sbt;
DELETE NOPROMPT BACKUP OF DATABASE COMPLETED BEFORE 'SYSDATE-7';

Crosschecking Archived Logs: Example

This example crosschecks all archived logs on disk (by using the preconfigured disk channel) and tape. If the logs are not found, then RMAN marks them as EXPIRED in the repository:

ALLOCATE CHANNEL FOR MAINTENANCE DEVICE TYPE sbt;
CROSSCHECK ARCHIVELOG ALL;

Crosschecking on Multiple Nodes of an Oracle Real Application Clusters Configuration: Example

In this example, you perform. a crosscheck of backups on two nodes of an Oracle Real Application Clusters configuration:

ALLOCATE CHANNEL FOR MAINTENANCE DEVICE TYPE DISK CONNECT 'SYS/change_on_install@inst1';
ALLOCATE CHANNEL FOR MAINTENANCE DEVICE TYPE DISK CONNECT 'SYS/change_on_install@inst2';
CROSSCHECK BACKUP;

Deleting on Disk and sbt Channels with One Command: Example

In this example, you delete a backup from both disk and tape:

# back up datafile to disk and tape
BACKUP DEVICE TYPE DISK DATAFILE 1 TAG "weekly_bkup";
BACKUP DEVICE TYPE sbt DATAFILE 1 TAG "weekly_bkup";

# manually allocate sbt channel and disk channel
ALLOCATE CHANNEL FOR MAINTENANCE DEVICE TYPE DISK;
ALLOCATE CHANNEL FOR MAINTENANCE DEVICE TYPE sbt;
DELETE BACKUPSET TAG "weekly_bkup";