Oracle redo log switches per hour alert


The Redo Log Switches Per Hour alert notifies you when its configured condition is met on Oracle instances so you can investigate and respond.

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Alert summary

  • Platform: Oracle
  • Alert category: Disk
  • Default enabled: true
  • Default evaluation frequency: Minute
  • Threshold label: Switches/hour
  • Unit: switches/hour

What Mini DBA checks

Mini DBA describes this alert as: Excessive redo log switches per hour High frequency (>4-6/hour) indicates undersized redo logs causing checkpoint storms and performance degradation Remediation: Increase redo log file size Mini DBA evaluates this alert once a minute so changes are detected quickly.

How this alert helps

This alert reports excessive Oracle redo-log switches. Frequent switches can mean the redo groups are undersized for the workload and may create checkpoint and archive pressure.

When to enable it

Enable it once the instance has a normal workload baseline. It is especially useful on busy OLTP, reporting, and integration systems where resource pressure can quickly become user-visible.

Threshold guidance

Threshold meaning: Switches/hour. Major threshold: 6 switches/hour. Minor threshold: 4 switches/hour. Comparison direction: over. For an over-threshold alert, decreasing a threshold makes that severity fire sooner; increasing it tolerates more load or pressure. Set the minor threshold as an early-warning level and the major threshold at the highest acceptable value for the service.

Remediation for an active alert

Confirm the switch rate and redo generation, review redo-group size and count, and check checkpoint and archive performance. Resize or add redo groups through an approved Oracle change when the logs are too small; deleting unrelated files does not correct excessive switches.

Investigation workflow

  1. Record the switch rate, redo generated per hour, redo-group sizes, and archive completion time.
  2. Correlate switches with workload bursts, checkpoints, archive pressure, and Data Guard lag.
  3. Validate the target redo size and group layout in a safe change plan.
  4. Confirm that switch frequency and checkpoint pressure improve after the change.

Avoiding alert noise

Storage alerts should usually stay enabled even on quiet systems because the impact of missing them is high. Tune warning thresholds to leave enough time for approval, provisioning, and validation, especially when storage changes are handled by another infrastructure team.

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