Tuesday, July 25, 2017

Oracle Recovery Manager Features: BACKUP AS COPY

What is the advantage backup as copy feature in RMAN?

RMAN(Recovery Manager) utility creates backup in the form of backupsets or backup pieces by default.RMAN utility also allows other method which is similar to user managed hot backup. It can be acheived using 'BACKUP AS COPY' command.Using "Backup as Copy" RMAN creates backup in the form of image copies. However, we do not need to put the database in begin backup/end backup mode as in Conventional Hot Backup.

Syntax for Datafile Backup using Backup as copy:

RMAN> backup as copy datafile 1 format '/backup/data/datafile01.dbf' ;



Another advantage of this feature is that it allows to create image copy of control file.

 RMAN> backup as copy current controlfile format 'F:\CntrlFile_Bkp.ctl';  


How do we identify backups taken  as Image copies using RMAN?

Use "LIST COPY" Command. "LIST BACKUP" only gives a list of backup sets which were created using default RMAN backup Methos.

Syntax:

RMAN> LIST COPY;

Saturday, July 08, 2017

ADOP Options: cleanup_mode

ADOP cleanup_mode

Run with adop cleanup phase.

Provides control over the extent of cleanup operations.
If no value is specified, cleanup is performed in standard mode, which does the same as quick mode but also drops obsolete code objects.

Values: quick/full

Purpose:

cleanup_mode=quick performs the minimum necessary cleanup to complete the online patching cycle. Use this mode if you want to start a new online patching cycle as soon as possible.

cleanup_mode=full performs all possible cleanup tasks for maximum recovery of space from unused database editions, objects and columns. Full cleanup is required after aborting an online patching cycle.

Usage:

adop phase=cleanup cleanup_mode=full
adop phase=cleanup cleanup_mode=quick

ADOP Options: actualize_all


Whenever adop prepare phase is initiated, a new patch edition is created in the database.During Online patching (ADOP) : An additional column ZD_EDITION_NAME is populated in the seed tables.As we do more online patching cycles, the number of entries for database editions will increase. This affects system performance and also increases cleanup time.When the number of old database editions reaches 25 or more, you should consider dropping all old database editions by running the adop actualize_all phase and then performing a full cleanup.

To drop older database editions, follow the below steps:

$ adop phase=prepare
$ adop phase=actualize_all
$ adop phase=finalize finalize_mode=full
$ adop phase=cutover
$ adop phase=cleanup cleanup_mode=full





How to Restore context file in oracle applications?

Scenario: Your Applications context file is either accidentally deleted or Corrupted. You do not have any latest backup of context file available.

Below are the steps to recreate context file 

The Applications context file can be retrieved by running the adclonectx.pl script.

perl /clone/bin/adclonectx.pl retrieve

Above script prompts for Database connection Info, apps username/password , Available Context files and the location to which context files can be restored.When prompted for the context file to be retrieved, select the option of retrieving the Applications tier context file that has been lost and retrieve it to the default location as in $CONTEXT_FILE parameter.

The above command can be used only when INST_TOP the is still intact. Incase if INST_TOP is also lost, the Applications tier context file may be retrieved as follows:

Execute the following command on the Database tier:
perl /appsutil/clone/bin/adclonectx.pl retrieve

When prompted for the context file to be retrieved, select the option of retrieving the Applications tier context file that has been lost.Choose the location to any writeable location and copy the restored context file to the value specified in $CONTEXT_FILE parameter on Application Tier.

To retrieve the Database tier context file,

Execute the following command on the Database tier:
perl /appsutil/clone/bin/adclonectx.pl retrieve

When prompted for the context file to be retrieved, select the Database tier context file and retrieve it to the default location ($CONTEXT_FILE on DB node).