Archiver Process (ARCn)
Preserving Your Redo Logs for Recovery 📚
🧾 What Is ARCn?
Archiver processes (ARCn) run only when the database is in ARCHIVELOG mode with automatic archiving enabled. Their job is to archive online redo log files to ensure that redo logs are safely saved before being reused.
🛠️ What Does ARCn Do?
| 🔧 Function | 📌 Details |
|---|---|
| 📥 Archive Online Logs | ARCn archives filled online redo log files so LGWR can overwrite them safely. |
| 🧑🤝🧑 Multiple Processes | Multiple ARCn processes (ARC0–ARC9 and ARCa–ARCt) may run concurrently to keep up with archiving load. |
| ⚙️ Configurable Count | The LOG_ARCHIVE_MAX_PROCESSES parameter controls how many ARCn processes start initially. |
| 🌐 Multiple Destinations | Supports multiple archive log destinations; Oracle recommends one ARCn process per destination. |
🧩 Additional Notes
- ARCn runs as either a thread or OS process, based on system configuration.
- Can have up to 31 archive destinations, with corresponding ARCn processes.
- Increasing the number of ARCn processes helps during heavy workloads, like bulk data loads.
🔒 Why ARCn Matters
- Prevents redo log overwrites until logs are safely archived.
- Essential for point-in-time recovery and backup consistency.
- Supports high availability and disaster recovery by maintaining archived redo logs.
📘 Tip of the Day:
Check archive log status using views like V$ARCHIVED_LOG and monitor ARCn processes with V$PROCESS to ensure archiving keeps pace with your workload.