Configuration, monitoring and management of Oracle Rman

1. The concept of the channel

A channel represents a stream of data to a device (disk or tape) and produces a corresponding server session on the target database or a secondary database instance (server sessions)

Multiple channels generate multiple server sessions, which will complete backup, restore, and recovery operations, and so on

Channels are divided into disk channels for backup or restore to disk (disk channel), Backup to tape channel (SBT)

Channels must be allocated before backups and restores are performed on the database

ALLOCATE Channel command starts a server process at the target database, and must define the I/O type used by the server process to perform a backup or restore operation

In fact, it is through channel to control the behavior of backup and recovery

The role of channel control commands:

Controlling the OS resources used by Rman

Influence degree of parallelism

Specify the throttling value for I/O bandwidth (set limit read rate parameter)

Defines the limit of the size of the backup slice (set limit Kbytes)

Specifies the limit value for the currently open file (set limit maxopenfiles)

2. Automatic channel allocation

You can use the following commands to automatically assign channels, and Rman automatically assigns channels based on these configurations once Rman sets the following parameters

CONFIGURE DEVICE TYPE ... PARALLELISM

CONFIGURE DEFAULT DEVICE TYPE

CONFIGURE CHANNEL

Assuming that backup DataFile 1 is performed at the Rman prompt, Rman assigns the channel to it using the preconfigured channel parameters

These commands backup, restore, and delete automatically allocate channels based on values set by the Configure command when running in a non-run block

But the command in the run block requires manual allocation of channels

--Change the default device type

rman> CONFIGURE DEFAULT DEVICE tyep to SBT;

--Configuring the degree of parallelism for the automatic allocation channel

rman> CONFIGURE DEVICE TYPE DISK PARALLELISM 3;

--Configure automatic channel options

rman> CONFIGURE CHANNEL DEVICE TYPE DISK

2> FORMAT = '/backup/rman/%u ';

rman> CONFIGURE CHANNEL DEVICE TYPE DISK

2> maxpiecesize 3G;

--Demo, change device type to SBT and then back to default

Rman> show default device type; --Displays the value of the default device type

RMAN configuration parameters are:

CONFIGURE DEFAULT DEVICE TYPE to DISK; # Default

Rman> Configure default device type to SBT; --Resets the default device type value to SBT

New RMAN configuration parameters:

CONFIGURE DEFAULT DEVICE TYPE to ' sbt_tape ';

New RMAN configuration parameters are successfully stored

Rman> show default device type; --Displays the value of the changed default device type

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RMAN configuration parameters are:

CONFIGURE DEFAULT DEVICE TYPE to ' sbt_tape ';

Rman> Configure default device type clear; --Place default device type as default

Old RMAN configuration parameters:

CONFIGURE DEFAULT DEVICE TYPE to ' sbt_tape ';

RMAN configuration parameters are successfully reset to default value

Rman> show default device type;

RMAN configuration parameters are:

CONFIGURE DEFAULT DEVICE TYPE to DISK; # Default

3. Manually allocate the channel

At least one channel needs to be allocated for commands such as Backup,copy,restore,recover

Assigning a channel starts a service process on the server where the target database is located, and the allocated channel actually specifies the concurrency degree

You can specify backups to different media, and you can specify read and write speeds when manual channels are used

Rman> RUN {

2> ALLOCATE CHANNEL ch1 TYPE Disk

3> BACKUP datafile 1,2,4

4> FORMAT '/u01/app/oralce/rmanbak/users_%u.bak ';}

The following example allocates a channel and uses a different channel for different data files to complete the backup work

Rman> RUN {

2> Allocate channel CH1 device type disk;

3> Allocate channel CH2 device type disk;

4> Allocate channel CH3 device type disk;

5> Backup

6> Incremental Level 0

7> (datafile 1,4 channel CH1)

8> (datafile 2,3 channel CH2)

9> (datafile 5,6 channel CH3);

10> alter system archive log current