Initiate a secondary log backup

This topic describes how to initiate a secondary log backup in two scenarios based on whether the log splitting feature is enabled to split log backups into pieces.

Secondary log backup when log splitting is enabled

In physical backup and restore, the content of the backup directory can be split. To resolve the problem of insufficient capacity on the backup storage media, you can perform a secondary log backup on the split content.

Perform a secondary backup on a single backup directory

To perform a secondary backup on a single backup directory, you can specify a backup_piece to back up. To archive the secondary backup to a destination that differs from the one specified for backup_backup_dest, you can specify another destination in the secondary backup statement.

Execute the following statement to perform a secondary backup on a single backup directory:

obclient> ALTER SYSTEM BACKUP BACKUPPIECE [=N] [backup_backup_dest = uri];

In the statement:

• N specifies the piece_id of the log backup to be backed up.

• [backup_backup_dest = uri] specifies the destination for the secondary backup. OSS and NFS can be used as the backup media.

  If backup_backup_dest has been set before secondary backup, you can disregard this parameter. Log backup data is archived to the directory specified in backup_backup_dest by default.

  If backup_backup_dest is not set before secondary backup, this parameter must be specified.

  For more information about the configuration method and description of backup_backup_dest, see Preparations for secondary backup.

For example:

• Back up the log backup whose piece_id is 1 to the file:///data/nfs/backup_backup directory.

obclient> ALTER SYSTEM BACKUP BACKUPPIECE 1 backup_backup_dest = 'file:///data/nfs/backup_backup';

Perform a secondary backup on multiple backup directories

Execute the following statements to perform a secondary backup on multiple backup directories:

• Perform a secondary backup on all directories or specified directories in the backup piece.

obclient> ALTER SYSTEM BACKUP BACKUPPIECE ALL [backup_backup_dest = 'xxxxx'];

obclient> ALTER SYSTEM BACKUP BACKUPPIECE ALL NOT BACKED UP N TIMES backup_backup_dest = 'xxxxx';

In the statements:

• ALL indicates that all backup_set_id and piece_id directories whose file_status is AVAILABLE will be included in the secondary backup.

  Note

  You can view the file status in the CDB_OB_BACKUP_PIECE_FILES view.

• The NOT BACKED UP N TIMES parameter indicates that data that has been backed up N times will not be included in the secondary backup. N indicates the number of times.

• If the NOT BACKED UP N TIMES parameter is specified in the command, the backup_backup_dest parameter must also be specified. Otherwise, the backup_backup_dest parameter does not need to be specified, and the backup data is archived to the directory specified by the backup_backup_dest parameter by default.

Secondary log backup when log splitting is not enabled

During a secondary log backup in which log splitting is not enabled, the system saves logs from the source backup location to the destination backup location.

1. Log on to the sys tenant as the root user.

2. Set the log_archive_checkpoint_interval parameter for backup_backup_dest_option to set the interval of the working thread for the secondary backup.

   The backup_backup_dest_option parameter specifies parameters related to secondary backup, and the log_archive_checkpoint_interval parameter specifies the interval for performing secondary log backup operations.

   For example, you can set log_archive_checkpoint_interval to two hours to perform a secondary log backup every two hours.

   For more information about the log_archive_piece_switch_interval parameter for backup_backup_dest_option, see Preparations for secondary backup.

   For more information about backup_backup_dest_option, see backup_backup_dest_option.

3. Start the worker thread for secondary log backup.

   obclient> ALTER SYSTEM START BACKUP ARCHIVELOG;
   

   Note

   After the worker thread is started, you can execute the ALTER SYSTEM STOP BACKUP ARCHIVELOG; statement to stop it.