12Copyright © 2005, Oracle. All rights reserved.
Proactive Maintenance
12-2 Copyright © 2005, Oracle. All rights reserved.
Objectives
After completing this lesson, you should be able to do the following:
• Set warning and critical alert thresholds
• Use server-generated alerts
• Collect and use baseline metrics
• Manage the Automatic Workload Repository (AWR)
• Use the Automatic Database Diagnostic Monitor
• Describe the advisory framework
12-3 Copyright © 2005, Oracle. All rights reserved.
Proactive Maintenance
AutomaticWorkload
Repository
Serveralerts
Automatedtasks
Advisoryframework
Data warehouseof the database
Automatic collection of important statistics
Direct memoryaccess
Automatic Proactive
Efficient
12-4 Copyright © 2005, Oracle. All rights reserved.
Introduction of Concepts and Related Tasks
• Thresholds and metric baselines
• Enabling metric baselining
• Server-generated alerts
• Creating and testing an alert
• Automatic Workload Repository (AWR)
• Managing the AWR
• Automatic Database Diagnostic Monitor (ADDM)
• Advisory framework
• Automated maintenance tasks
> BaselineAlertAWRADDMAdvisorsAutoTasks
12-5 Copyright © 2005, Oracle. All rights reserved.
Introducing Terminology
• Baseline: Data gathered of a “normal running database” for performance comparison
• Metric: Rate of change in a cumulative statistic
• Threshold: A boundary value against which metric values are compared
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Cyclic Nature of Workloads
End of day 1
OLTP DW
Metric
Time
ValueEnd of day 2 End of day 3
…
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Overview of Thresholds and Metric Baselines: Fixed Thresholds
Fixedthresholds
OLTP DW
Metric
Time
Value
Deviations missed
Critical
Warning
End of day 1 End of day 2 End of day 3
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Overview of Thresholds and Metric Baselines: Adaptive Thresholds
Adaptive thresholdsEnd ofbaseline
Metric
Time
Value
Deviations captured
Critical
Warning
Normal
Grouping
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Metric Baselines and Thresholds: Concepts
Baseline period
Staticbaseline
Movingwindow
Metric threshold
FixedAdaptive
Timegrouped
Percent ofMAX
Significancelevel
Automaticallycomputedbaselinestatistics
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Editing Thresholds
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Enabling Metric Baselining
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Creating Static Metric Baselines
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Server-Generated Alerts
Serveralerts
queue.
Metric exceeds
threshold.
AWR
Enterprise Manager
Oracle instance
Baseline> Alert
AWRADDMAdvisorsAutoTasks
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Server-Generated Alert Types
MMON
85% Warning
97% Critical Cleared
Cleared
Alert
SnapshotToo Old
ResumableSession
Suspended
Recovery Area Low On
Free Space
Metric based
Event based
Threshold(stateful)
alerts
Nonthreshold (stateless)
alerts
DBA_OUTSTANDING_ALERTS DBA_ALERT_HISTORY
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Default Server-Generated Alerts
ResumableSession
Suspended
SnapshotToo Old
Recovery AreaLow On
Free Space
85% Warning97% Critical
Tablespacespace usage
Database Control:SYSTEM metrics
Tablespace
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Creating and Testing an Alert
1. Specify a threshold.
2. Create a test case.
3. Check for an alert.
21
3
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Where We Are
Thresholds and metric baselines
Enabling metric baselining
Server-generated alerts
Creating and testing an alert
• Automatic Workload Repository (AWR)
• Managing the AWR
• Automatic Database Diagnostic Monitor (ADDM)
• Advisory framework
• Automated maintenance tasks
12-19 Copyright © 2005, Oracle. All rights reserved.
Automatic Workload Repository (AWR)
• Built-in repository of performance information
• Snapshots of database metrics taken every 60 minutes and retained for 7 days
• Foundation for all self-management functions
MMONIn-memorystatistics
Snapshots
AWRSGA
60 minutes
BaselineAlert
> AWRADDMAdvisorsAutoTasks
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AWR Infrastructure
SGA
V$ DBA_*
ADDM Self-tuningcomponent
Self-tuningcomponent
…Internal clients
External clientsEM SQL*Plus …
Efficientin-memorystatisticscollection
AWRsnapshotsMMON
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AWR Snapshot Sets
DBMS_WORKLOAD_REPOSITORY.CREATE_BASELINE ( - start_snap_id IN NUMBER , end_snap_id IN NUMBER , baseline_name IN VARCHAR2);
Relevant periodin the past
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Enterprise Manager and AWR
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Managing the AWR
• Retention period:– The default is 7 days.– Consider storage needs.
• Collection interval:– The default is
60 minutes.– Consider storage needs and performance impact.
• Collection level:– Basic (disables most of ADDM functionality) – Typical (recommended)– All (adds additional SQL tuning information to
snapshots)
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Automatic Database Diagnostic Monitor (ADDM)
• Runs after each AWR snapshot
• Monitors the instance; detects bottlenecks
• Stores results within the AWR
Snapshots
ADDM
AWR
EMADDM results
BaselineAlertAWR
> ADDMAdvisorsAutoTasks
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ADDM Findings
1
2
3
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ADDM Recommendations
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Advisory Framework
ADDM
SQL Tuning Advisor
SQL Access Advisor
Memory
Space
PGA Advisor
SGA
Segment Advisor
Undo Advisor
Buffer CacheAdvisor
Library CacheAdvisor
PGA
Backup MTTR Advisor
BaselineAlertAWRADDM
> AdvisorsAutoTasks
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SQL Tuning and Access Advisors
DBA
Poorly performingSQL statement
SQL TuningAdvisor
RestructuredSQL statement
Add indexes or materialized views.
Rewrite the SQL statement.
Correct setup flaws.
How can I make it run
faster?
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Memory Advisors
• Shared pool
• Database buffer cache
• Program Global Area (PGA)
• Tip: Enable ASMM.
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Segment Advisor
• Entiretablespace
• Individualschemaobjects
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Enterprise Manager and Advisors
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The DBMS_ADVISOR Package
Procedure Description
CREATE_TASK Creates a new task in the repository
DELETE_TASK Deletes a task from the repository
EXECUTE_TASK Initiates execution of the task
INTERRUPT_TASK Suspends a task that is currently executing
GET_TASK_REPORT Creates and returns a text report for the specified task
RESUME_TASK Causes a suspended task to resume
UPDATE_TASK_ATTRIBUTES
Updates task attributes
SET_TASK_PARAMETER Modifies a task parameter
MARK_RECOMMENDATION Marks one or more recommendations as accepted, rejected, or ignored
GET_TASK_SCRIPT Creates a script of all the recommendations that are accepted
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Automated Maintenance Tasks
• Scheduler initiates jobs.
• Jobs run in default maintenance window.
• Limit maintenance impact on normal operation by using Resource Manager.
Maintenance examples:
• Gathering optimizer statistics
• Gathering segment information
• Backing up database
BaselineAlertAWRADDMAdvisors
> AutoTasks
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Proactive Maintenance
A review of major elements working together:
AutomaticWorkload
Repository
Serveralerts
Automatedtasks
Advisoryframework
Automatic Proactive
Efficient
12-36 Copyright © 2005, Oracle. All rights reserved.
Summary
In this lesson, you should have learned how to:
• Set warning and critical alert thresholds
• Use server-generated alerts
• Collect and use baseline metrics
• Manage the Automatic Workload Repository (AWR)
• Use the Automatic Database Diagnostic Monitor
• Describe the advisory framework
12-37 Copyright © 2005, Oracle. All rights reserved.
Practice Overview: Proactive Maintenance
This practice covers configuring your database for proactive maintenance by:
• Configuring an alert and testing it
• Enabling metric baselines
• Creating a static metric baseline to compute statistics
• Deleting the baseline
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