Flash Recovery Area Usage

Job details

Name:	Flash Recovery Area Usage
Platform:	Oracle
Category:	Capacity
Description:	Checks space usage in the flash recovery area.
Long description:	Task checks space usage in the flash recovery area.
Version:	2.5
Default schedule:	10 * * *
Requires engine install:	Yes
Compatibility tag:	.[type=‘instance’ & databasetype=‘oracle’]/.[version like ‘10.2%’ & hasengine=‘YES’ & _priv_read_v_flash_recovery_area_usage = ‘1′]

Parameters

Name	Default value	Description
warning threshold	80	Warning threshold for flash recovery area usage (percentage).
alarm threshold	95	Alarm threshold for flash recovery area usage (percentage).
warning threshold (GB)	5	Minimum of free space (in GB) for the flash recovery area. If the amount of free space falls below this parameter value, and at the same time the amount of free space in percent falls below the “warning threshold” parameter value, the alert will return a WARNING.
alarm threshold (GB)	2	Minimum of free space (in GB) for the flash recovery area. If the amount of free space falls below this parameter value, and at the same time the amount of free space in percent falls below the “alarm threshold” parameter value, the alert will return an ALARM.
history threshold	30	The number of days the statistics will be kept in the history table.

Job Summary

Purpose: The job monitors the Flash Recovery Area (FRA) usage in Oracle databases specifically for version 10.2 and checks if the FRA is appropriately sized and utilized, preventing potential space allocation issues that could affect database operations.
Why: This job is important to ensure that the FRA, which is essential for database recovery operations, does not reach capacity. Overfilling the FRA can lead to inability in managing backups and archives effectively, which might cause database failure or data loss situations.
Manual checking: You can check this manually in the database by issuing the following SQL commands:

select round(to_number(value)/1048576/1000) "Total Size GB",
       round(sum(PERCENT_SPACE_USED),1) "Percent Space Used",
       round((100 - sum(PERCENT_SPACE_USED)),1) "Percent Free Space" 
from V$FLASH_RECOVERY_AREA_USAGE, v$parameter
where name = 'db_recovery_file_dest_size';

Implementation Details

The monitoring job creates history tables and procedures specific to the instance to regularly check the current FRA usage against thresholds defined for warnings and alarms.
It uses complex SQL queries embedded in PL/SQL procedures to calculate the percentage of space used, the amount of free space in GB, and determines the alert status based on predefined thresholds.
It updates monitoring values accordingly and maintains a historical record of FRA usage which can be used to analyze trends over time.

Alerts and Thresholds

The job implements alerts based on two parameters:
- Percentage of FRA used.
- Absolute free space remaining in GB.
Warning is issued if the usage percentage exceeds the warning threshold or the free space drops below the specified GB threshold.
An alarm condition is similar but set for higher usage percentages and lower free space thresholds.

Report Generation

A report template included in the job configuration presents detailed views of FRA usage including:
- FRA usage statistics.
- Historical data pertaining to space usage.
- Initialization parameters relevant to FRA configuration.
- Recommended RMAN commands to manage space in the FRA.

Report Section	Description
Flash Recovery Area Usage	Displays current usage statistics and file types within the FRA, highlighting potential space reclaimable and the number of files.
Flash Recovery Usage History	Shows historical data of space usage in the FRA, allowing for trend analysis and space management planning.
Initialization Parameters	Lists Oracle initialization parameters that impact FRA, such as the ‘db_recovery_file_dest_size’ which denotes maximum space for recovery files.

| RMAN Crosscheck | Provides RMAN commands to free up space or verify the state of recovery files if manual intervention is necessary.

Dependencies and Automations

Job dependencies include self-referential checks ensuring that each task component triggers as expected without manual interferences.
Auto cleanup features are enabled to maintain optimal performance and accuracy in monitoring by removing outdated historical data.

This job setup ensures a proactive management approach towards critical database recovery components, reducing the risk of unscheduled downtimes or data loss due to FRA overflow.