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Spotlight on Oracle 10.10 - Release Notes

Background Processes Panel

 

The Background Processes panel displays the following key Oracle background processes:

  • Database Writer (DBWRn).
  • The Recovery Writer (RVWRn).
  • The Log Writer (LGWRn).
  • The Archiver (ARCHn).
  • Data Guard Overhead and Apply Lag
  • Predictive Diagnostics.

Note: The n value in each process icon indicates the number of processes there are of that type.

Panel Components

Database Writer

Oracle database files. The level of fill in this component corresponds to the overall space utilization in the database.

The Excessive RBS Activities Alarm may occur if the RBS (rollback segments) activity exceeds a threshold.

Recovery Writer

The Recovery Writer process is responsible for writing to the flashback logs in the flash recovery area.

These logs are required to restore the database to a previous point in time by using the "flashback" option for Oracle databases (Oracle 10g and later).

Redo Log Writer

The Redo log writer (LGWR) writes the redo buffer blocks from SGA to redo log files on the hard disk.

An alarm can become current on this process if log switch waits occur (Log Switch Time Alarm), or if the average redo I/O time exceeds a threshold (Average Time to Sync a Redo Log Entry Alarm).

Improve Redo Log Writer Performance

Archiver

The Archiver process (ARCH) copies redo logs to an archive directory to allow later point-in-time recovery if needed.

For information on improving archiver performance, see Improve Redo Log Writer Performance | Optimizing archiving.

Data Guard Overhead

This control is applicable to environments where Oracle Data Guard is installed. It shows the overhead of Data Guard on the primary database.

The design is similar to the Average Active Sessions (AAS) guage.

  • Dark Shaded Area - Amount of time sessions spend waiting on data guard.
  • Light Shaded Area - Amount of time sessions spend on other tasks.
  • White Line - CPU Limit.

A value greater than the CPU limit, indicates potential performance issues. This is shown on the Average Active Sessions gauge as either of the colored bars passing the vertical white line. How far the colored bar has passed the vertical white line indicates the severity of the performance issue. A value far greater than the CPU limit indicates that the database is experiencing bottlenecks.

Note: Alarms on this component are raised on the Spotlight on Oracle Data Guard Home Page, not the Spotlight on Oracle home page.

Apply Lag

This control is applicable to environments where Oracle Data Guard is installed. The apply lag measures the difference in elapsed time from when the last applied change became visible on the standby and that same change was first visible on the primary. The value is taken from v$dataguard_stats.

An alarm raised on this control indicates an alarm on Spotlight on Oracle Data Guard - NOT necessarily an alarm on the apply lag. For more information on the alarm raised, open the Spotlight on Oracle Data Guard home page(s) for this Primary database. The severity of the alarm on this control matches the highest severity alarm raised on Spotlight on Oracle Data Guard.

Predictive Diagnostics

Predictive Diagnostics allows Spotlight to collect and analyze performance metrics for an Oracle database in order to predict its future behavior. In doing so, it identifies:

  • SQL statements ("degrading SQL") whose performance may not scale adequately in the future as data volumes and SQL execution rates increase.
  • Waiting events ("bottlenecks") that may in the future affect database throughput and response time.
  • Database resources (CPU, memory, and disk I/O) whose limitations may in the future affect database performance.

The status of Predictive Diagnostics for this connection is:

Color Status
Green Predictive Diagnostics is installed and the required Predictive Diagnostics schema exists on the database instance.
Yellow

Predictive Diagnostics is installed, but has encountered a problem. Possible problems may include:

Grayed out Predictive Diagnostics is not available. Re-run the Oracle User Wizard to install Predictive Diagnostics.

Predictive Diagnostics

Data Flows

The flows between the Background Processes panel and the Disk Storage panel represent:

Physical Writes/s (Database Writer)

The dataflow from the Background Processes panel to the Database Files component in the Disk Storage Panel shows the rate at which blocks are being written from the SGA to disk by the database writer (DBWR) process.

This is identical to the Database Writer dataflow from the SGA panel to the Background Processes panel.

Recovery Writes/s (Recovery Writer)

The rate of I/O write operations to the flash recovery area by the RVWR processes. Writes will increase as database change activity increases. This may occur when:

  • The database updates the flashback logs.
  • The database writes to the archived redo logs (if archive logs are stored in the flash recovery area).

This is identical to the Flashback IO/s dataflow from the SGA panel to the Background Processes panel.

Redo Writes/s (Redo Log Writer)

The dataflow from the Background Processes panel to the Redo Logs component in the Disk Storage Panel shows the rate at which redo log blocks are being written by the Redo Log Writer (LGWR) process.

This is identical to the Redo Log Writer dataflow from the SGA panel to the Background Processes panel.

Archived Copy Rate (Disk Storage)

Both Archiving Rate dataflows between the Background Processes and Disk Storage panels represent the rate at which the Archiver copies data from the redo log files and saves it to the archive log.

For information on improving archiver performance, see Improve Redo Log Writer Performance | Optimizing archiving.

 

Related Topics

Spotlight on Oracle Home Page

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