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Dbvisit Archive Log Management Module (AMM)

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1. Introduction


The Dbvisit Standby Archive Log Management Module (AMM) fully automates the management and monitoring of the Oracle database archive log space on the primary as well as the Dbvisit ARCHDEST location on the standby server.

By default when creating a new DDC file in version 8, the AMM module is disabled for the primary database.  This is to ensure the Dbvisit AMM module does not interfere with archive log purging options implemented as part of RMAN backup strategies.  We do however recommend that you leave at least one day worth of archive logs on the primary server and not to delete all archive logs following a backup, as they may not have been transferred to the standby database server.


Unlike the Oracle database files location, the Oracle archive logs location needs to be monitored and managed constantly to ensure the database continues its optimal operation. If the disk space available to Oracle archive logs is used up, the whole database will "freeze" and not allow any update or insert operation.

Dbvisit Standby Archive Log Management Module includes the following options:

  1. Alerts through email when Oracle archive logs have reached a set threshold of available disk space.
  2. Can delete Oracle archive logs after a set number of days.
  3. Can ensure that only x number of Oracle archive log files remain on server.
  4. Can delete Oracle archive logs after available disk space has been used up to ensure continual database operation.
  5. Ensures the Oracle archive logs have been sent to standby database before removing any logs.
  6. Can integrate with Backup software to ensure logs have been backed up before removing.


Dbvisit Standby is not replacing your backup scripts or backup software.

It is important that you still backup your database and archive log to different storage or a tape device.

On this page:

2.  AMM and Multiple Standby Databases

In case of multiple standby databases, Dbvisit Standby checks if a log has been transferred to all active standby databases before deleting it on the primary.

A standby database is considered to be active if a Dbvisit process has run within the last DBV_LAST_RUN_OFFSET days to ship logs to this database from the primary.

Note the default value: 

DBV_LAST_RUN_OFFSET=1


3.  Dbvisit Standby AMM processing overview


The order of precedence in managing the log files are:

  1. If there are log files older than DAYS_TO_KEEP_ARCHSOURCE, then delete these.
  2. If there are more log files than NUM_ARCHSOURCE_TO_KEEP, then delete these (oldest ones first).
  3. If there are more logs that have been backed up by RMAN at least ARCHSOURCE_BACKUP_COUNT times, then delete these.
  4. If the THRESHOLD_ARCHSOURCE < mount point fullness criteria is met, then mark archives for deletion (oldest ones first). The number of archives marked for deletion is HOWMANY_ARCHSOURCE. The archives will only be deleted if DELETE_ARCHSOURCE=Y. After deletion of the archives, and the criteria is still met (THRESHOLD_ARCHSOURCE < mount point fullness), then mark more archives for deletion (number of archives marked for deletion will be again HOWMANY_ARCHSOURCE, and oldest ones first). This process will continue until criteria is no longer met.

If DELETE_ARCHSOURCE=N, then only a warning email will be sent. No archives will be deleted when the THRESHOLD_ARCHSOURCE < mount point fullness criteria is met.Setting variable DELETE_ARCHSOURCE=N has no influence over DAYS_TO_KEEP_ARCHSOURCE and NUM_ARCHSOURCE_TO_KEEP. These will still delete archive files when their criteria are met.

4.  Dbvisit Standby AMM log file

The Dbvisit Standby Archive Log Management Module (AMM) produces a separate log file to the Dbvisit Standby database processing. The log file can be found in the same location as Dbvisit Standby database log file. The log file is called _arch_management.log. The location is determined by the LOGDIR and LOGDIR_DR settings in the DDC file.

5.  Primary AMM Configuration Variables

This section provides an overview of the variables that can be configured for the AMM module with regards to the Primary Database.

Variables are sorted alphabetically in the table below

Variable Name

Meaning

ARCHSOURCE_BACKUP_COUNT

Specify the number of times an archive log has to be backed up by RMAN before Dbvisit Standby deletes it from the primary server.

To disable this setting, set to 0 which is the default value.

Example:

ARCHSOURCE_BACKUP_COUNT = 0


ARCHSOURCE_MANAGEMENT

Specify if the AMM module to manage the archive log files are turned on or off on the primary server.

Possible Values:

  • Yes
    Enable the AMM module on primary server.

  • No (default)
    Disable the AMM module on primary server.

Example:

ARCHSOURCE_MANAGEMENT= Yes


DAYS_TO_KEEP_ARCHSOURCE

Specify the number of days to keep the Oracle log files on the primary server. If this value (in days) are reached, the log files will be removed from the server.

To disable this setting, set to 0, if you are not sure, set to 7.

Make sure you have sufficient disk space to store the archive logs.

See also the ARCHDEST parameter under the standby server variable section for more detail


Example:

DAYS_TO_KEEP_ARCHSOURCE = 7


DELETE_ARCHSOURCE_THRESHOLD

Specify if archive log files should be deleted once the percentage threshold (THRESHOLD_ARCHSOURCE) on the primary server is reached.

Once the threshold is reached oldest archive log files are deleted first. 

There is no verification that these log files have been backed up. Dbvisit Standby does not perform backups, this should be configured outside the Dbvisit Standby product.

Possible Values:

  • Yes
    Let Dbvisit Standby delete archive log files once percentage threshold is met. 

  • No
    Dbvisit Standby will only alert when percentage threshold is met (no archive log files will be deleted). 

If you are not sure, set to No.

Example:

DELETE_ARCHSOURCE_THRESHOLD = No


This setting has no influence whether (archive) log files are deleted for DAYS_TO_KEEP_ARCHSOURCE or NUM_ARCHSOURCE_TO_KEEP.

These settings will delete (archive) log files once the percentage threshold is met.

FRA_THRESHOLD_ARCHSOURCE

Specifies the threshold in percentage (%) of how much FRA (flash/fast recovery area) space may be taken up by the archive log files on disk before an alert is triggered on the primary server. A value of 80 means at 80% FRA space threshold is reached, an alert will be triggered.

Please specify threshold as an integer. 

Example:

   FRA_ THRESHOLD_ARCHSOURCE = 80


NUM_ARCHSOURCE_TO_KEEP

Specifies the number of archive log files to keep on the primary server. Log files greater than this number will be removed (oldest first).

To disable this setting, set to 0. If you are not sure, set to 0 (disable).

Example:

    NUM_ARCHSOURCE_TO_KEEP = 0


THRESHOLD_ARCHSOURCE

Specifies the threshold in percentage (%) of how much disk space may be taken up by the archive log files on disk before an alert is triggered on the primary server. A value of 80 means at 80% space threshold is reached, an alert will be triggered.

Please specify threshold as an integer. 

Example:

    THRESHOLD_ARCHSOURCE = 80




6.  Standby AMM Configuration Variables

This section provides an overview of the variables that can be configured for the AMM module with regards to the Standby Database.

Please see Archive log Management Module (AMM) for more information on AMM.


Variables are sorted alphabetically in the table below

Variable Name

Meaning

ARCHDEST_MANAGEMENT

Specifies if the AMM module to manage the archive log files is turned on or off on the standby server.

Possible Values:

  • Yes
    Enable AMM module on the standby server.

  • No
    Disable AMM module on the standby server.

If you are not sure, set to Yes.

Example:

    ARCHDEST_MANAGEMENT= Yes


DAYS_TO_KEEP_ARCHDEST

Specifies the number of days to keep the Oracle log files on the standby server. After this the log files will be removed from the server.

This is specific to the Dbvisit Standby ARCHDEST location. Please see ARCHDEST in the Standby Variable section.

To disable this setting, set to 0. If you are not sure, set to 7.

Example:

DAYS_TO_KEEP_ARCHDEST = 7


DELETE_ARCHDEST_THRESHOLD

Specifies if archive log files should be deleted once the percentage threshold (THRESHOLD_ARCHDEST) on the standby server is reached.

Once the threshold is reached oldest (archive) log files are deleted first. 

There is no verification that these log files have been backed up, this (backups) is outside the scope of Dbvisit Standby


Possible Values:

  • Yes
    Let Dbvisit Standby delete archive log files once percentage threshold is met. 

  • No
    Dbvisit Standby will only alert when percentage threshold is met (no log files will be deleted). 

If you are not sure, set to No.

Example:

DELETE_ARCHDEST_THRESHOLD = No


This setting has no influence whether archive log files are deleted for DAYS_TO_KEEP_ARCHDEST or NUM_ARCHDEST_TO_KEEP.

These settings will delete archive log files once the percentage threshold is met.

NUM_ARCHDEST_TO_KEEP

Specifies the number of archive log files to keep on the standby server. Log files greater than this number will be removed (oldest first).

To disable this setting, set to 0. If you are not sure, set to 0 (disable).

Example:

NUM_ARCHDEST_TO_KEEP = 0


THRESHOLD_ARCHDEST

Specifies the threshold in percentage (%) of how much disk space may be taken up by the archive log files on disk before an alert is triggered on the standby server.

This parameter is specific to the Dbvisit Standby ARCHDEST location


A value of 80 means that if the 80% disk space threshold is reached, an alert will be triggered. If you are not sure, set to 80.

Example:

THRESHOLD_ARCHDEST = 80




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