• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer navigation

The Geek Diary

  • OS
    • Linux
    • CentOS/RHEL
    • Solaris
    • Oracle Linux
    • VCS
  • Interview Questions
  • Database
    • oracle
    • oracle 12c
    • ASM
    • mysql
    • MariaDB
  • DevOps
    • Docker
    • Shell Scripting
  • Big Data
    • Hadoop
    • Cloudera
    • Hortonworks HDP

Oracle RMAN 11g New Feature – MultiSection Backups

by admin

What are MultiSection Backups?

By default, RMAN uses the parameters like filesize and number of available channels to decide whether to produce a single or multidatafile backupset with 1 or more backuppieces. In a multisection backup, RMAN creates a backup set in which each backup piece contains the blocks from one datafile section. A file section is a contiguous range of blocks in a datafile.

The purpose of multisection backups is to enable RMAN to back up a single file in parallel. RMAN divides the work among multiple channels, with each channel backing up one file section. Backing up a file in separate sections can improve both the performance and restartability of backups of bigfiles and/or datafiles which are of a big size.

Example

This example will show the principle of the Multi Section Backups for only 1 datafile. Doing it for only 1 datafile is making the output easier to read and explain.

RMAN> report schema;

Report of database schema for database with db_unique_name V110

List of Permanent Datafiles
===========================
File Size(MB) Tablespace RB segs Datafile Name
---- -------- -------------------- ------- ------------------------
1 300 SYSTEM YES /oradata/v110/system01.dbf
2 120 SYSAUX NO /oradata/v110/sysaux01.dbf
3 200 UNDOTBS1 YES /oradata/v110/undotbs01.dbf
4 20 RECOVER_TEST NO /oradata/v110/recover_test.dbf

List of Temporary Files
=======================
File Size(MB) Tablespace Maxsize(MB) Tempfile Name
---- -------- -------------------- ----------- --------------------
1 20 TEMP 32767 /oradata/v110/temp01.dbf

A SECTION SIZE of 100m will split each datafile in 100Mb backupsets and will be backed up by 2 channels. So 1 backupset with 3 pieces for datafile 1.

RMAN> backup section size 100m datafile 1;

Starting backup at 11-JAN 06:13:29
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=138 device type=DISK
allocated channel: ORA_DISK_2
channel ORA_DISK_2: SID=141 device type=DISK
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00001 name=/oradata/v110/system01.dbf
backing up blocks 1 through 16384
channel ORA_DISK_1: starting piece 1 at 11-JAN 06:13:31
channel ORA_DISK_2: starting full datafile backup set
channel ORA_DISK_2: specifying datafile(s) in backup set
input datafile file number=00001 name=/oradata/v110/system01.dbf
backing up blocks 16385 through 32768
channel ORA_DISK_2: starting piece 2 at 11-JAN 06:13:31
channel ORA_DISK_2: finished piece 2 at 11-JAN 06:13:37
piece handle=/backups/v110/V110_36i77c4b_2_1 tag=TAG20070111T061330 comment=NONEchannel ORA_DISK_2: backup set complete, elapsed time: 00:00:06
channel ORA_DISK_2: starting full datafile backup set
channel ORA_DISK_2: specifying datafile(s) in backup set
input datafile file number=00001 name=/oradata/v110/system01.dbf
backing up blocks 32769 through 38400
channel ORA_DISK_2: starting piece 3 at 11-JAN 06:13:38
channel ORA_DISK_1: finished piece 1 at 11-JAN 06:13:39
piece handle=/backups/v110/V110_36i77c4b_1_1 tag=TAG20070111T061330 comment=NONEchannel ORA_DISK_1: backup set complete, elapsed time: 00:00:08
channel ORA_DISK_2: finished piece 3 at 11-JAN 06:13:39
piece handle=/backups/v110/V110_36i77c4b_3_1 tag=TAG20070111T061330 comment=NONEchannel ORA_DISK_2: backup set complete, elapsed time: 00:00:08
Finished backup at 11-JAN 06:13:39

Starting Control File and SPFILE Autobackup at 11-JAN 06:13:39
piece handle=/backups/v110/V110_c-1689207191-20070111-07 comment=NONE
Finished Control File and SPFILE Autobackup at 11-JAN 06:13:40

The SECTION information is available in V$BACKUP_DATAFILE and RC_BACKUP_DATAFILE.

SQL> select block_size, blocks, blocks_read, section_size
from v$backup_datafile
where file#=1;

BLOCK_SIZE BLOCKS     BLOCKS_READ SECTION_SIZE
---------- ---------- ----------- ------------
8192       11040      16384         16384

The RMAN tracefile shows :

DBGMISC: krmkbck: files=1 blocks=38400 sets=1 setsize=38400 hard_lim=0 hard_kb=0
...
DBGMISC: krmkbck: backup set list: [06:19:20.759]
DBGMISC: 1 SL blocks=0 blksize=0 files=0 bscomp=0
DBGMISC: 2 SL blocks=38400 blksize=0 files=1 bscomp=0
DBGMISC: [completion time set][multi-section]
DBGMISC: 1 DF fno=1 crescn=10 blksize=8192 blocks=38400 rfno=1
DBGMISC: fn=/oradata/v110/system01.dbf
DBGMISC: ts=SYSTEM, flags=KRMKDF_INBACKUP
DBGMISC: fedata: sta=0x0e crescn=10
DBGMISC: fhdata: ckpscn=251298 rlgscn=1
DBGMISC: device=2080 blocks=38400
DBGMISC: node=NULL_NODE
.....
DBGMISC: krmfmxi, filesize=38400, secsize=16384, seccnt=3, stamp=611561961, count=111

The output of the section backup is a normal backuppiece. If send to tape than compression and deduplication will still work, but on this backuppiece only, not on the whole datafile.

NOTE: Oracle 12c supports multisection incremental backups.

Filed Under: oracle, Oracle 11g, oracle 12c

Some more articles you might also be interested in …

  1. Managing Rollback/Undo Segments in AUM (Automatic Undo Management)
  2. How To Change SYS user password for oracle database instance
  3. Oracle 20c New Feature: PDB Point-in-Time Recovery or Flashback to Any Time
  4. How to Install and configure OSWatcher Black Box (OSWbb)
  5. Oracle ASM 11gR2 instance is unable to start due to missing ASM spfile
  6. Error: ORA-16810: multiple errors or warnings detected for the database
  7. Oracle Database : What Is The Search Order For The LDAP.ORA File
  8. Using Rule Sets in Oracle Database Vault
  9. Beginners Guide to RMAN compression for backups
  10. Common Init.ora Parameters and Unix, Linux Kernel Parameters and Relationship Between Them

You May Also Like

Primary Sidebar

Recent Posts

  • grpck command – Remove corrupt or duplicate entries in the /etc/group and /etc/gshadow files.
  • xxd command – Expressed in hexadecimal form
  • sesearch: command not found
  • macof: command not found

© 2022 · The Geek Diary

  • Archives
  • Contact Us
  • Copyright