Oracle Learning Rman (vi) Backup set backup slice

We look back at the files that were generated when the database was backed up.

rman> backup database; starting backup at 2015/07/08 00:58:27using  channel ora_disk_1channel ora_disk_1: starting full datafile backup  Setchannel ora_disk_1: specifying datafile (s)  in backup setinput datafile  file number=00001 name=/u01/app/oracle/oradata/devdb/system01.dbfinput datafile file  number=00002 name=/u01/app/oracle/oradata/devdb/sysaux01.dbfinput datafile file  Number=00005 name=/u01/app/oracle/oradata/devdb/example01.dbfinput datafile file number= 00003 name=/u01/app/oracle/oradata/devdb/undotbs01.dbfinput datafile file number=00006  name=/u01/app/oracle/oradata/devdb/idx01.dbfinput datafile file number=00004 name=/ u01/app/oracle/oradata/devdb/users01.dbfchannel ora_disk_1: starting piece 1 at  2015/07/08 00:58:28channeL ora_disk_1: finished piece 1 at 2015/07/08 01:00:33piece handle=/u01 /app/oracle/fast_recovery_area/devdb/backupset/2015_07_08/o1_mf_nnndf_tag20150708t005827_bsr19n9z_.bkp  tag=tag20150708t005827 comment=nonechannel ora_disk_1: backup set complete,  Elapsed time: 00:02:05channel ora_disk_1: starting full datafile backup  setchannel ora_disk_1: specifying datafile (s)  in backup setincluding  current control file in backup setincluding current spfile in  backup setchannel ora_disk_1: starting piece 1 at 2015/07/08  01:00:34channel ora_disk_1: finished piece 1 at 2015/07/08 01:00:35piece  handle=/u01/app/oracle/fast_recovery_area/devdb/backupset/2015_07_08/o1_mf_ncsnf_tag20150708t005827_ bsr1flnq_.bkp tag=tag20150708t005827 comment=nonechannel ora_disk_1: backup set complete, elapsed time:  00:00:01finished backup at 2015/07/08 01:00:35

Two files generated altogether

/u01/app/oracle/fast_recovery_area/devdb/backupset/2015_07_08/o1_mf_nnndf_tag20150708t005827_bsr19n9z_.bkp/u01 /app/oracle/fast_recovery_area/devdb/backupset/2015_07_08/o1_mf_ncsnf_tag20150708t005827_bsr1flnq_.bkp

The first file contains a backup of 6 dbf files, and the second file contains the backup of the control files and SPFile. These two files Rman is called a backup set.

Backup set: Rman is used to save a unique format for a backup set that can contain one or more physical files.

There are three types of backup sets:

• Data files: Can contain data files and control files, but do not contain archived logs.

• Archive log: Contains only archived logs and cannot contain data files or control files.

• Backup set: The backup set can be backed up in Rman, which means that the backup set contains backup sets.

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Features of the backup set

• You can create a backup set by using the Backup command. The Filesperset parameter controls the number of data files that are contained in the backup set.

• A backup set typically contains multiple files.

• You can write backup sets to disk or to tape.

• To extract files from a backup set, you must use a restore operation.

• A data file backup set can be either an incremental or a full backup.

• The backup set does not contain blocks that have never been used.

Let's just imagine, if you follow the backup database above, what's the problem with all the data files generating only one backup set file? When the database is very large, the resulting file is also huge. Even if we don't consider whether the operating system has a limit on file size. A file of that size is also very difficult to manage and maintain.

To this end, Oracle introduces the concept of backup slices. If you pay close attention to the backup information above, you will find such words.

Piece handle=/u01/app/oracle/fast_recovery_area/devdb/backupset/2015_07_08/o1_mf_nnndf_tag20150708t005827_ Bsr19n9z_.bkp

Piece the meaning of instant backup tablets. Backup slices physically split the backup set into one or more files. We look at:

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Features of the backup slice

• A backup slice is a file in the backup set.

• A backup slice can contain chunks of data from multiple data files.

• You can use the parameter maxpiecesize to control the maximum size of the backup slice.
  

This article is from the "Ding Dong" blog, please be sure to keep this source http://lqding.blog.51cto.com/9123978/1680339

Oracle Learning Rman (vi) Backup set backup slice