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Oracle 11g – taking High Availability to
the next level
Gavin Soorma
Senior Oracle DBA,
HBOS Australia
An HA Wish List ….
• Recover Faster from media failure – reduce unplanned downtime
• Reduce the cost of inevitable human error
• Reduce storage and network bandwidth associated with backups
• Reduce the risk and cost associated with change
• Perform as many tasks as possible online without planned
outages
• Ensure application stability for end users
• And ….save $$$$ for the business
What can Oracle 11g deliver?
• Reduced backup durations – compressed backups, incremental
backups from Standby database
• Reduced recovery durations – Data Recovery Advisor
• Proactive automatic database health monitoring
• Increased application availability through efficient SQL plan
stability and optimizer plan management
• Real time testing with production data – reduced cost as well as
risk of deploying change
• Enhanced online application maintenance
• Flashback Transaction enhancements
… and more …..
Snapshot Standby
• Updateable standby database created from Physical Standby
• Physical Standby >> Snapshot Standby >> Test >>Physical
Standby
• Snapshot Standby is open in read-write mode
• Redo received from Primary but not applied
• After converting back to Physical Standby, resynchronized with
Primary by applying accumulated redo data
• Testing with real time production data on a ready made real time
environment
• No need to perform production clones
Snapshot Standby
DGMGRL> show configuration
Configuration
Name:
gavin
Enabled:
YES
Protection Mode:
MaxAvailability
Databases:
apex
- Primary database
apexdg - Physical standby database
Fast-Start Failover: DISABLED
Current status for "gavin":
SUCCESS
Snapshot Standby
DGMGRL> convert database 'apexdg' to snapshot standby;
Converting database "apexdg" to a Snapshot Standby database, please
wait...
Database "apexdg" converted successfully
DGMGRL> show configuration
Configuration
Name:
gavin
Enabled:
YES
Protection Mode:
MaxAvailability
Databases:
apex
- Primary database
apexdg - Snapshot standby database
Fast-Start Failover: DISABLED
Current status for "gavin":
SUCCESS
Snapshot Standby
apexdg:/u01/oracle/scripts> export ORACLE_SID=apex
apex:/u01/oracle/scripts> sqlplus sh/SH
SQL*Plus: Release 11.1.0.6.0 - Production on Fri Sep 19 09:40:55 2008
Copyright (c) 1982, 2007, Oracle.
All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> create table test_redo_apply
2 as select * from all_objects;
Table created.
SQL> select count(*) from test_redo_apply;
COUNT(*)
---------56467
Snapshot Standby
apex:/u01/oracle/scripts> export ORACLE_SID=apexdg
apexdg:/u01/oracle/scripts> sqlplus sh/SH
SQL*Plus: Release 11.1.0.6.0 - Production on Fri Sep 19 09:33:29 2008
Copyright (c) 1982, 2007, Oracle.
All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> create table test_snapshot
2 as select * from all_objects;
Table created.
SQL> select count(*) from test_snapshot;
COUNT(*)
---------56467
Snapshot Standby
DGMGRL>
convert database 'apexdg' to physical standby;
Converting database "apexdg" to a Physical Standby database, please wait...
Operation requires shutdown of instance "apexdg" on database "apexdg"
Shutting down instance "apexdg"...
Database closed.
Database dismounted.
ORACLE instance shut down.
Operation requires startup of instance "apexdg" on database "apexdg"
Starting instance "apexdg"...
ORACLE instance started.
Database mounted.
Continuing to convert database "apexdg" ...
Operation requires shutdown of instance "apexdg" on database "apexdg"
Shutting down instance "apexdg"...
ORA-01109: database not open
Database dismounted.
ORACLE instance shut down.
Operation requires startup of instance "apexdg" on database "apexdg"
Starting instance "apexdg"...
ORACLE instance started.
Database mounted.
Database "apexdg" converted successfully
DGMGRL>
Snapshot Standby
apex:/u01/oracle/scripts> sqlplus sh/SH@apex
SQL*Plus: Release 11.1.0.6.0 - Production on Fri Sep 19 09:46:17 2008
Copyright (c) 1982, 2007, Oracle.
All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> select count(*) from test_snapshot;
select count(*) from test_snapshot
*
ERROR at line 1:
ORA-00942: table or view does not exist
Snapshot Standby
apexdg:/u01/oracle/scripts> dgmgrl
DGMGRL for IBM/AIX RISC System/6000: Version 11.1.0.6.0 - 64bit
Production
Copyright (c) 2000, 2005, Oracle. All rights reserved.
Welcome to DGMGRL, type "help" for information.
DGMGRL> connect sys/oracle
Connected.
DGMGRL> edit database 'apexdg' set state='apply-off';
Succeeded.
DGMGRL> exit
Snapshot Standby
apexdg:/u01/oracle/scripts> sqlplus / as sysdba
SQL*Plus: Release 11.1.0.6.0 - Production on Fri Sep 19 09:48:38 2008
Copyright (c) 1982, 2007, Oracle.
All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> alter database open read only;
Database altered.
SQL> conn sh/SH@apexdg
Connected.
SQL> select count(*) from test_redo_apply;
COUNT(*)
---------56467
Data Recovery Advisor
• Decreases the amount of time required to recover from
failure
• Automatically diagnoses data failures and provides alerts
• Automatically assesses the extent and impact of the failure
• Automatically suggests multiple repair options based on the
environment and the extent of the assessed damage.
• Automates the repair process and verifies if the repair was
successful.
Automatic Health Monitoring
• Automatic Health Monitoring proactively detects problems early in
their life-cycle and notifies the DBA of the user impact and
recommended action to take
• Proactively checks the health of the database and identifies any
issues before it impacts end users
Data Structure Integrity Check
Data Block Integrity Check
Redo Integrity Check
Undo Segment Integrity Check
Dictionary Integrity Check
• Part of the 11g Support Workbench and can be run in reactive as
well as manual mode
Data Recovery Advisor
apex:/u01/oracle/scripts> cd /u02/oradata/apex/
apex:/u02/oradata/apex> rm example01.dbf
apex:/u02/oradata/apex> sqlplus sh/SH@apex
SQL*Plus: Release 11.1.0.6.0 - Production on Fri Sep 19 10:03:34 2008
Copyright (c) 1982, 2007, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> select count(*) from test_redo_apply;
select count(*) from test_redo_apply
*
ERROR at line 1:
ORA-01116: error in opening database file 6
ORA-01110: data file 6: '/u02/oradata/apex/example01.dbf'
ORA-27041: unable to open file
IBM AIX RISC System/6000 Error: 2: No such file or directory
Additional information: 3
Data Recovery Advisor
apex:/u02/oradata/apex> rman target /
Recovery Manager: Release 11.1.0.6.0 - Production on Fri Sep 19 10:04:44
2008
Copyright (c) 1982, 2007, Oracle. All rights reserved.
connected to target database: APEX (DBID=1312143933)
RMAN> LIST FAILURE;
using target database control file instead of recovery catalog
List of Database Failures
=========================
Failure ID Priority Status
Time Detected Summary
---------- -------- --------- ------------- ------162
HIGH
OPEN
19-SEP-08
One or more non-system
datafiles are missing
Data Recovery Advisor
RMAN>
ADVISE FAILURE;
List of Database Failures
=========================
Failure ID Priority Status
Time Detected Summary
---------- -------- --------- ------------- ------162
HIGH
OPEN
19-SEP-08
One or more non-system datafiles are missing
analyzing automatic repair options; this may take some time
allocated channel: ORA_SBT_TAPE_1
channel ORA_SBT_TAPE_1: SID=107 device type=SBT_TAPE
Mandatory Manual Actions
========================
no manual actions available
Optional Manual Actions
=======================
1. If file /u02/oradata/apex/example01.dbf was unintentionally renamed or moved, restore it
Automated Repair Options
========================
Option Repair Description
------ -----------------1
Restore and recover datafile 6
Strategy: The repair includes complete media recovery with no data loss
Repair script: /u01/oracle/diag/rdbms/apex/apex/hm/reco_1541621723.hm
Data Recovery Advisor
RMAN> REPAIR FAILURE PREVIEW;
Strategy: The repair includes complete media recovery with no data loss
Repair script: /u01/oracle/diag/rdbms/apex/apex/hm/reco_1541621723.hm
contents of repair script:
# restore and recover datafile
sql 'alter database datafile 6 offline';
restore datafile 6;
recover datafile 6;
sql 'alter database datafile 6 online
Data Recovery Advisor
RMAN>
REPAIR FAILURE NOPROMPT;
Strategy: The repair includes complete media recovery with no data loss
Repair script: /u01/oracle/diag/rdbms/apex/apex/hm/reco_1541621723.hm
...
...
sql statement: alter database datafile 6 offline
Starting restore at 19-SEP-08
using channel ORA_SBT_TAPE_1
using channel ORA_DISK_1
channel ORA_SBT_TAPE_1: starting datafile backup set restore
channel ORA_SBT_TAPE_1: specifying datafile(s) to restore from backup set
channel ORA_SBT_TAPE_1: restoring datafile 00006 to /u02/oradata/apex/example01.dbf
channel ORA_SBT_TAPE_1: reading from backup piece 76jqvhr1_1_1
channel ORA_SBT_TAPE_1: piece handle=76jqvhr1_1_1 tag=TAG20080919T090744
channel ORA_SBT_TAPE_1: restored backup piece 1
channel ORA_SBT_TAPE_1: restore complete, elapsed time: 00:01:05
Finished restore at 19-SEP-08
Starting recover at 19-SEP-08
using channel ORA_SBT_TAPE_1
using channel ORA_DISK_1
Data Recovery Advisor
starting media recovery
channel ORA_SBT_TAPE_1: starting archived log restore to default destination
channel ORA_SBT_TAPE_1: restoring archived log
archived log thread=1 sequence=59
channel ORA_SBT_TAPE_1: reading from backup piece 77jqvi1r_1_1
channel ORA_SBT_TAPE_1: piece handle=77jqvi1r_1_1 tag=TAG20080919T091123
channel ORA_SBT_TAPE_1: restored backup piece 1
channel ORA_SBT_TAPE_1: restore complete, elapsed time: 00:00:07
archived log file name=/u03/oradata/apex/arch/arch.1_59_664991234.log thread=1
archived log file name=/u03/oradata/apex/arch/arch.1_60_664991234.log thread=1
archived log file name=/u03/oradata/apex/arch/arch.1_61_664991234.log thread=1
...
...
archived log file name=/u03/oradata/apex/arch/arch.1_70_664991234.log thread=1
archived log file name=/u03/oradata/apex/arch/arch.1_71_664991234.log thread=1
archived log file name=/u03/oradata/apex/arch/arch.1_72_664991234.log thread=1
archived log file name=/u03/oradata/apex/arch/arch.1_73_664991234.log thread=1
archived log file name=/u03/oradata/apex/arch/arch.1_74_664991234.log thread=1
media recovery complete, elapsed time: 00:00:07
Finished recover at 19-SEP-08
sql statement: alter database datafile 6 online
repair failure complete
RMAN>
sequence=59
sequence=60
sequence=61
sequence=70
sequence=71
sequence=72
sequence=73
sequence=74
Automatic Health Monitoring
SQL> SELECT name FROM v$hm_check WHERE internal_check='N';
NAME
----------------------------------------------------------DB Structure Integrity Check
Data Block Integrity Check
Redo Integrity Check
Transaction Integrity Check
Undo Segment Integrity Check
Dictionary Integrity Check
6 rows selected.
Automatic Health Monitoring
SQL> select run_id from
V$HM_FINDING where TIME_DETECTED like '19-SEP%';
RUN_ID
---------5988
SQL> select name from v$hm_run where run_id=5988;
NAME
-------------------------------HM_RUN_5988
SQL> select name,time_detected,description,damage_description from V$HM_FINDING
2 where run_id=5988;
NAME
-------------------------------TIME_DETECTED
--------------------------------------------------------------------------DESCRIPTION
-------------------------------------------------------------------------------DAMAGE_DESCRIPTION
-------------------------------------------------------------------------------Missing datafile
19-SEP-08 10.10.14.474095 AM
Datafile 6: '/u02/oradata/apex/example01.dbf' is missing
Some objects in tablespace EXAMPLE might be unavailable
RMAN Enhancements
•
Network-enabled Database Duplication
A clone database on a remote site can now be easily created directly over the network
with the enhanced DUPLICATE command without existing backups.
Reduces DBA time and effort and eliminates the storage capacity required at the
remote site for the copy.
•
Optimized Undo backup
Reduced overall backup time and storage by not backing up undo that applies to
transactions that have already been committed.
•
Fast Incremental Backups on Physical Standby Database
RMAN can use the block change tracking file on Physical Standby database for incremental
backups – backups can be easily offloaded to standby sites to conserve primary host
resources
Network-enabled Database Duplication
DUPLICATE TARGET DATABASE TO dupdb
FROM ACTIVE DATABASE
DB_FILE_NAME_CONVERT
'/oracle/oradata/prod/','/scratch/oracle/oradata/dupdb/'
SPFILE
PARAMETER_VALUE_CONVERT
'/oracle/oradata/prod/', '/scratch/oracle/oradata/dupdb/'
SET SGA_MAX_SIZE '300M'
SET SGA_TARGET '250M'
SET LOG_FILE_NAME_CONVERT
'/oracle/oradata/prod/redo/',
'/scratch/oracle/oradata/dupdb/redo/';
RMAN Enhancements
•
Creation and Recovery of Long-Term Backups Improved
Long-term backups created with the KEEP option only back up the archive logs needed
to make the backup consistent. No further archive log backups are retained.
•
Multisection Backups - Parallel Backup and Restore for Very Large Files
Improves the performance of backups and restores of very large data files by
parallelizing the workload for each file by dividing the data file into sub sections.
•
Fast Backup Compression
In addition to the Oracle Database 10g backup compression algorithm (BZIP2), RMAN now
supports the ZLIB algorithm, which offers 40% better performance, with a trade-off of no more
than 20% lower compression ratio, versus BZIP2.
Online Application Maintenance
•
DDL with the WAIT Option
•
DDL commands require exclusive locks on internal structures.
•
Set via the WAIT option in the DDL_LOCK_TIMEOUT initialization
parameter.
•
WAIT option gives you more flexibility to define grace periods for such
commands to succeed instead of raising an error right away
•
Enhanced ADD COLUMN Functionality
•
Default values of columns are maintained in the data dictionary for
columns specified as NOT NULL.
•
Adding new columns with DEFAULT values and NOT NULL constraint no
longer requires the default value to be stored in all existing records.
•
Enables a schema modification in sub-seconds and independent of the
existing data volume, it also consumes no space
Online Application Maintenance
CREATE TABLE lock_tab (
id NUMBER
SQL>
);
2
3
Table created.
SQL>
INSERT INTO lock_tab VALUES (1);
1 row created.
**NOT COMMITED AT THIS STAGE**
SQL> ALTER TABLE lock_tab ADD (
description
); 2 3
VARCHAR2(50)
ALTER TABLE lock_tab ADD (
*
ERROR at line 1:
ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired
Online Application Maintenance
SQL> ALTER SESSION SET ddl_lock_timeout=30;
Session altered.
SQL> ALTER TABLE lock_tab ADD (
2
description VARCHAR2(50) );
**NO ERROR THIS TIME– SESSION WILL WAIT ...**
SQL> commit;
Commit complete.
SQL> ALTER TABLE lock_tab ADD (
2
description VARCHAR2(50)
3 );
Table altered.
Online Application Maintenance
crashdb:/u01/oracle> sql
SQL*Plus: Release 10.2.0.3.0 - Production on Thu Oct 2 10:06:53 2008
Copyright (c) 1982, 2006, Oracle. All Rights Reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bit Production
With the Partitioning and Data Mining options
SQL>
2
create table myobjects
as select * from dba_objects;
Table created.
SQL>
select count(*) from myobjects;
COUNT(*)
---------101580
SQL>
SQL>
2
set timing on
alter table myobjects
add (new_column varchar2(3) default 'YES' not null);
Table altered.
Elapsed: 00:00:31.68
Online Application Maintenance
apex:/u01/oracle>
sql
SQL*Plus: Release 11.1.0.6.0 - Production on Thu Oct 2 10:14:09 2008
Copyright (c) 1982, 2007, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL>
select count(*) from myobjects;
COUNT(*)
---------142676
SQL>
set timing on
SQL>
alter table myobjects
add (new_column varchar2(3) default 'YES' not null);
2
Table altered.
Elapsed:
00:00:00.93
Fine Grained Dependency Management
•
Finer Grained Dependencies
•
Pre11g, metadata recorded mutual dependencies between objects with the
granularity of the whole object
•
This means that dependent objects were sometimes invalidated when there
was no logical requirement to do so.
•
View V1 depends on Table T1 – Columns C1 and C2. if Column c3 is added,
V1 will get invalidated.
•
Oracle Database 11g records dependency metatdata at a finer level of
granularity reducing the consequential invalidation of dependent objects in
response to changes in the objects they depend upon
•
Results in increased application availability
Fine Grained Dependency Management
crashdb:/u01/oracle> sql
SQL*Plus: Release 10.2.0.3.0 - Production on Thu Oct 2 12:15:09 2008
Copyright (c) 1982, 2006, Oracle. All Rights Reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bit Production
With the Partitioning and Data Mining options
SQL> create table test_dependency
2 (col_a varchar2(10), col_b varchar2(10));
Table created.
SQL> create view test_dependency_vw
2 as select col_a from test_dependency;
View created.
SQL> alter table test_dependency add (col_c varchar2(10));
Table altered.
SQL> select status from user_objects where object_name='TEST_DEPENDENCY_VW';
STATUS
------INVALID
Fine Grained Dependency Management
apex:/u01/oracle/scripts> sql
SQL*Plus: Release 11.1.0.6.0 - Production on Thu Oct 2 12:22:19 2008
Copyright (c) 1982, 2007, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> create table test_dependency
2 (col_a varchar2(10), col_b varchar2(10));
Table created.
SQL> create view test_dependency_vw
2 as select col_a from test_dependency;
View created.
SQL> alter table test_dependency add (col_c varchar2(10));
Table altered.
SQL> select status from user_objects where object_name='TEST_DEPENDENCY_VW';
STATUS
------VALID
Flashback Enhancements
•
Block Recovery can now be performed from the Flashback Logs on disk.
•
Reduces recovery time by potentially eliminating time consuming
restores from tape to repair a few corrupt blocks.
•
Information Life Cycle management using Flashback Data Archives
•
Guaranteed retention of historical and archived data
•
No need to rely on UNDO tablespace data retention policies
•
Flashback Data archive stored in a tablespace and contains
transactional changes to every record in a table
•
Flashback Transaction can easily back out a transaction and its
dependent transactions.
•
DBMS_FLASHBACK.TRANSACTION_BACKOUT() procedure rolls back
a transaction and its dependent transactions while the database remains
online.
Flashback Transaction - Backout
SQL> INSERT INTO hr.regions VALUES (10,'Pole');
1 row created.
SQL> INSERT INTO hr.regions VALUES (20,'Moon');
1 row created.
SQL> commit;
Commit complete.
SQL> UPDATE hr.regions SET region_name='Two Poles'
WHERE region_id = 10;
1 row updated.
SQL> UPDATE hr.regions SET region_name='Two Moons' WHERE region_id=20;
1 row updated.
SQL> commit;
Commit complete.
Flashback Transaction - Backout
SQL>
UPDATE hr.regions SET region_name='Three Poles' WHERE region_id = 10;
1 row updated.
SQL> UPDATE hr.regions SET region_name='Three Moons' WHERE region_id=20;
1 row updated.
SQL> commit;
Commit complete.
SQL> select * from regions;
REGION_ID
---------1
2
3
4
10
20
REGION_NAME
------------------------Europe
Americas
Asia
Middle East and Africa
Three Poles
Three Moons
6 rows selected.
Flashback Transaction - Backout
SQL> select xid,operation from flashback_transaction_query
2 where table_name='REGIONS'
3 and trunc(start_timestamp)='02-OCT-2008';
XID
---------------0009001B000024EE
000A000200001C9F
000A000200001C9F
OPERATION
-------------------------------INSERT
UPDATE
UPDATE
SQL> BEGIN
DBMS_FLASHBACK.transaction_backout (numtxns
xids
options
END;
/ 2
3
4
5
6
BEGIN
*
ERROR at line 1:
ORA-55504: Transaction conflicts in NOCASCADE
ORA-06512: at "SYS.DBMS_FLASHBACK", line 37
ORA-06512: at "SYS.DBMS_FLASHBACK", line 70
ORA-06512: at line 2
=> 1,
=> xid_array('0009001B000024EE'),
=> DBMS_FLASHBACK.nocascade);
mode
Flashback Transaction - Backout
SQL> BEGIN
DBMS_FLASHBACK.transaction_backout (numtxns => 1,
xids
=> xid_array('0009001B000024EE'),
options => DBMS_FLASHBACK.cascade);
end;
/
PL/SQL procedure successfully completed.
SQL> select COMPENSATING_XID,DEPENDENT_XID,BACKOUT_MODE
2 FROM
dba_flashback_txn_state
3 WHERE xid = '0009001B000024EE';
COMPENSATING_XID DEPENDENT_XID
BACKOUT_MODE
---------------- ---------------- ---------------000A000200001CA2 0004001D00001D21 CASCADE
SQL> select * from hr.regions;
REGION_ID
---------1
2
3
4
REGION_NAME
------------------------Europe
Americas
Asia
Middle East and Africa
Flashback Data Archive – Total Recall
SQL> create tablespace archive_data
2 datafile '/u02/oradata/apex/archive_data01.dbf' size 1024m;
Tablespace created.
SQL> create flashback archive year1 tablespace archive_data
2 quota 500m retention 1 year;
Flashback archive created.
SQL> grant flashback archive on year1 to HR;
Grant succeeded.
SQL> conn HR/HR
Connected.
SQL> alter table regions flashback archive year1;
Table altered.
Flashback Data Archive – Total Recall
SQL> conn / as sysdba
Connected.
SQL> SELECT table_name, owner_name, flashback_archive_name, archive_table_name
FROM
dba_flashback_archive_tables;
TABLE_NAME
OWNER_NAME
FLASHBACK_ARCHIVE_NA ARCHIVE_TABLE_NAME
--------------- --------------- -------------------- -------------------REGIONS
HR
YEAR1
SYS_FBA_HIST_79593
SQL> SELECT flashback_archive_name, retention_in_days
FROM
dba_flashback_archive;
FLASHBACK_ARCHIVE_NA RETENTION_IN_DAYS
-------------------- ----------------YEAR1
365
SQL Plan Management
• Overcomes limitations with Stored Outlines (8i) and SQL Profiles
(10g)
• Guarantees plan stability by ensuring only accepted execution plans
are ever used by the CBO
• Once plans are accepted and evolved, all subsequent executions of
the same SQL statement will always use that plan unless a new plan
with a lower cost is made available by the CBO
• SMB – SQL Management Base – stores SQL text, its outline, bind
variables in SYSAUX tablespace.
OPTIMIZER_CAPTURE_SQL_PLAN_BASELINES
OPTIMIZER_USE_SQL_PLAN_BASELINES
Gathering and Publishing Statistics
•
Pre 11g,the statistics were automatically published once the gather was
completed.
•
New statistics can invalidate plans and can result in new (inefficient)
execution paths.
•
In 11g test the statistics before publishing them and ensure only
acceptable plans are used by the Optimizer
•
Gather Statistics >> Pending Statistics >> Published Statistics
•
Ensure plan stability and increased application availability
ASM Fast Mirror Resync
•
Pre 11g, temporary transient failures (cable disconnect) will cause disk to be
dropped from disk group straight away.
•
ASM would rebalance the disk group after dropping the disk – rebalance
again after adding disk once problem is rectified
•
Rebalancing operations increases I/O significantly.
•
ASM attribute ‘disk_repair_time’ now provides a window for repair – disk is
dropped if this window expires – default 3.6 hours
•
After disk is online, only extents that have been marked as modified
need to be rebalanced after failed disk joins disk group.
•
Once the disk is available, only the changed extents are written to
resynchronize the disk, rather than overwriting the contents of the entire disk
ALTER DISKGROUP dgroupA SET ATTRIBUTE ‘DISK_REPAIR_TIME’=‘3H’;
ASM Metadata Backup and Restore
• Pre Oracle 11g no backup of ASM meta data
• If disk group is lost, restore lost files via RMAN, but manually
recreate ASM disk group as well as user directories/templates
• 11g ASMCMD includes ASM metadata backup and restore
• Parses ASM fixed tables and views to get information on disk and
failure group configuration, templates and alias directory structure
ASMCMD> md_backup –b asm_metadata –g data
ASMCMD> md_restore –b asm_metadata –t full –g data
Miscellaneous
• Online Patching
• ASM Rolling Upgrade from 10g R2 to 11g
• Online redefinition of tables with MV’s and MV Logs
• ADRCI and Incident Packaging Service
• Rebuild indexes online without any exclusive lock at the
beginning and end of the operation
• SQL Repair Advisor – repair SQL statements causing ORA-600’s
by providing a customised SQL patch after recompiling and reexecuting SQL statement
Thanks for attending!!
GAVIN SOORMA
Senior Oracle DBA Specialist
HBOS Australia
Contact me at : 0417713124
or
[email protected]
QUESTIONS
ANSWERS