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This article mainly introduces "how to understand the channel allocation in RMAN". In the daily operation, I believe many people have doubts about how to understand the channel allocation in RMAN. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the doubts about "how to understand the channel allocation in RMAN". Next, please follow the editor to study!

Channel assignment in RMAN

The so-called channel: refers to the byte flow between the files of the target database and the physical device initiated and controlled by the server process. A channel is a session, and a session corresponds to a server process. All backup and restore operations are done by RMAN-connected server processes, or more specifically, by channels. There are two main forms of channel allocation: automatic channel allocation and manual channel allocation.

First, automatic channel allocation: automatic channel allocation means that the channel can be used without explicitly defining the details of the channel when executing the RMAN command. (actually use the preset or default settings)

1. View the default channel device type setting type

RMAN > show default device type

Using target database control file instead of recovery catalog

RMAN configuration parameters for database with db_unique_name PRAC are:

CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default

2. View the available device types (including the number of channels)

RMAN > show device type

RMAN configuration parameters for database with db_unique_name PRAC are:

CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default

Modify device backup parallelism:

RMAN > configure device type disk parallelism 2;-- set the device backup parallelism to 2 so that the backup starts with two channels.

New RMAN configuration parameters:

CONFIGURE DEVICE TYPE DISK PARALLELISM 2 BACKUP TYPE TO BACKUPSET

New RMAN configuration parameters are successfully stored

Restore the default settings:

RMAN > configure device type disk clear

Old RMAN configuration parameters:

CONFIGURE DEVICE TYPE DISK PARALLELISM 2 BACKUP TYPE TO BACKUPSET

RMAN configuration parameters are successfully reset to default value

3. View the channel configuration

RMAN > show channel

RMAN configuration parameters for database with db_unique_name PRAC are:

RMAN configuration has no stored or default parameters

Modify the channel configuration:

RMAN > configure channel device type disk maxpiecesize 2G;-- set the maximum backup slice size to 2G

New RMAN configuration parameters:

CONFIGURE CHANNEL DEVICE TYPE DISK MAXPIECESIZE 2 G

New RMAN configuration parameters are successfully stored

RMAN > configure channel 1 device type disk to destination'/ u01 image backup;-- set the backup path of channel 1 to'/ u01 bind backup.'

New RMAN configuration parameters:

CONFIGURE CHANNEL 1 DEVICE TYPE DISK TO DESTINATION'/ u01 Compact backup'

New RMAN configuration parameters are successfully stored

Restore the channel configuration:

RMAN > configure channel device type disk clear

Old RMAN configuration parameters:

CONFIGURE CHANNEL DEVICE TYPE DISK MAXPIECESIZE 2 G

Old RMAN configuration parameters are successfully deleted

RMAN > configure channel 1 device type disk clear

Old RMAN configuration parameters:

CONFIGURE CHANNEL 1 DEVICE TYPE DISK TO DESTINATION'/ u01 Compact backup'

Old RMAN configuration parameters are successfully deleted

Second, manual channel allocation: use the allocate channel command to allocate channels in the run running block. For example:

RMAN > run {

2 > allocate channel ch2 device type disk to destination'/ u01Universe backupCompact'

3 > allocate channel ch3 device type disk to destination'/ u01Universe backupCompact'

4 > backup

5 > (tablespace users channel ch2)

6 > (tablespace example channel ch3)

7 >}

Third, after the completion of the experiment, use the following command to delete all backup sets in the test library (never do so in the production library! )

Delete noprompt backup

Related knowledge supplement:

A byte stream is made up of bytes and a character stream is made up of characters. The character in Java consists of two bytes. Byte stream is the most basic, all the subclasses of InputStream and OutputStream are, mainly used to deal with binary data, it is processed by bytes, but in practice, a lot of data is text, and the concept of character stream is put forward, which is processed according to the encode of the virtual machine, that is, to convert the character set. When converting from a byte stream to a character stream, that is, when byte [] is converted to String, public String (byte bytes [], String charsetName) has a key parameter character set encoding, which is usually omitted, so the system uses the operating system default lang.

Streaming transmission mainly refers to parsing the whole audio, video and three-dimensional media and other multimedia files into compressed packets through a specific compression mode, which is transmitted sequentially or in real time from the video server to the user's computer. In the system of streaming transmission, users do not have to wait for the whole file to be downloaded, but only need to go through a few seconds or tens of seconds of startup delay to play and watch the compressed multimedia files on the user's computer after decompression equipment. At this point, the rest of the multimedia file will continue to be downloaded in the server in the background.

At this point, the study on "how to understand the channel allocation in RMAN" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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