Introduction
Have you ever encountered a situation where your Oracle database suddenly stops accepting new connections, and users start complaining that the application is down? One of the most common culprits behind this scenario is the dreaded ORA-00257: archiver error.
Recently, we faced this exact scenario with one of our production databases during a high-transaction period. The database was running fine until the archive log destination reached 100% capacity, bringing all operations to a halt. In this guide, I’ll walk through the complete diagnosis and resolution process with real commands and outputs from an actual implementation.
Understanding ORA-00257
The complete error message typically appears as:
ORA-00257: archiver error. Connect internal only, until freed.
This error occurs when Oracle’s archiver process (ARCn) cannot write archive logs to the configured destination. The database enters a restricted state to prevent data loss, allowing only SYSDBA connections.
Common Causes
| Cause | Frequency | Resolution Complexity |
|---|---|---|
| Archive destination full (disk space) | Most Common (70%) | Easy |
| Archive destination not accessible | Common (15%) | Medium |
| Flash Recovery Area (FRA) full | Common (10%) | Easy |
| Permission issues on archive directory | Rare (5%) | Easy |
Step-by-Step Diagnosis
Step 1: Connect as SYSDBA
When ORA-00257 occurs, normal connections are blocked. You must connect as SYSDBA:
$ sqlplus / as sysdba
SQL*Plus: Release 19.0.0.0.0 - Production on Sat Dec 6 10:30:15 2025
Version 19.25.0.0.0
Connected to:
Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Version 19.25.0.0.0Step 2: Check Archive Destination Status
First, identify which archive destination is causing the problem:
SQL> SELECT dest_name, status, error, space_used, space_limit FROM v$archive_dest_status WHERE status != 'INACTIVE';
Step 3: Check Disk Space
Verify the actual disk space on your archive destination:
$ df -h /u01/archFilesystem Size Used Avail Use% Mounted on
/dev/sdb1 100G 100G 0 100% /u01/archAs we can see, the archive destination is completely full – this is our root cause.
Step 4: Check Flash Recovery Area (If Using FRA)
If you’re using Flash Recovery Area, check its utilization:
SQL> SELECT name,
space_limit/1024/1024/1024 AS limit_gb,
space_used/1024/1024/1024 AS used_gb,
ROUND((space_used/space_limit)*100,2) AS pct_used
FROM v$recovery_file_dest;NAME LIMIT_GB USED_GB PCT_USED
------------------------------ ---------- ---------- ----------
+FRA 200 198.50 99.25Resolution Methods
Method 1: Delete Obsolete Archive Logs (Recommended)
The safest approach is to use RMAN to delete archive logs that have already been backed up:
$ rman target /
RMAN> DELETE ARCHIVELOG ALL COMPLETED BEFORE 'SYSDATE-7';
RMAN> CROSSCHECK ARCHIVELOG ALL;
RMAN> DELETE EXPIRED ARCHIVELOG ALL;allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=245 device type=DISK
List of Archived Log Copies for database with db_unique_name PRODDB
=====================================================================
Key Thrd Seq S Low Time
------- ---- ------- - ---------
1245 1 8934 A 01-DEC-25 1246 1 8935 A 01-DEC-25
...
Do you really want to delete the above objects (enter YES or NO)? YES
deleted archived log
archived log file name=/u01/arch/1_8934_1156789012.dbf
...
Deleted 156 objects✓ Best Practice: Always ensure archive logs are backed up before deletion.
Use DELETE ARCHIVELOG ALL BACKED UP 2 TIMES TO DEVICE TYPE DISK; for safer cleanup.
Method 2: Increase FRA Size (If Using FRA)
If your Flash Recovery Area is full, you can increase its size:
SQL> ALTER SYSTEM SET db_recovery_file_dest_size = 300G SCOPE=BOTH;System altered.
Method 3: Add Additional Archive Destination
If you need immediate relief, add a secondary archive destination:
SQL> ALTER SYSTEM SET log_archive_dest_2='LOCATION=/u02/arch_backup' SCOPE=BOTH;
SQL> ALTER SYSTEM SET log_archive_dest_state_2=ENABLE SCOPE=BOTH;Method 4: Temporarily Switch to NOARCHIVELOG (Emergency Only)
⚠️ Warning: This should ONLY be used in extreme emergencies when data loss is acceptable. You will lose the ability for point-in-time recovery.
SQL> SHUTDOWN IMMEDIATE;
SQL> STARTUP MOUNT;
SQL> ALTER DATABASE NOARCHIVELOG;
SQL> ALTER DATABASE OPEN;Verification
After applying the fix, verify the archiver is functioning normally:
Check Archive Process Status
SQL> SELECT process,
status,
sequence#
FROM v$managed_standby
WHERE process LIKE 'ARC%';PROCESS STATUS SEQUENCE#
--------- ------------ ----------
ARC0 CONNECTED 0
ARC1 CLOSING 9156
ARC2 CONNECTED 0
ARC3 CONNECTED 0Verify Archive Destination
SQL> SELECT dest_name,
status,
error
FROM v$archive_dest_status
WHERE status != 'INACTIVE';DEST_NAME STATUS ERROR
-------------------- ---------- -------------------------
LOG_ARCHIVE_DEST_1 VALIDTest New Connections
$ sqlplus scott/tiger@PRODDB
SQL> SELECT 'Connection successful' FROM dual;'CONNECTIONSUCCESSFUL'
----------------------
Connection successfulPrevention: Automated Monitoring
To prevent ORA-00257 from occurring again, implement proactive monitoring:
Shell Script for Archive Destination Monitoring
#!/bin/bash
# archive_monitor.sh - Monitor archive destination usage
THRESHOLD=80
USAGE=$(df -h /u01/arch | tail -1 | awk '{print $5}' | sed 's/%//')
if [ $USAGE -gt $THRESHOLD ]
then echo "WARNING: Archive destination at ${USAGE}% usage" | \ mail -s "Archive Space Alert - $(hostname)" dba-team@company.com fiOracle Scheduler Job for FRA Monitoring
SQL> BEGIN
DBMS_SCHEDULER.CREATE_JOB ( job_name => 'MONITOR_FRA_SPACE',
job_type => 'PLSQL_BLOCK',
job_action => 'BEGIN FOR r IN (SELECT ROUND((space_used / space_limit)*100) pct
FROM v$recovery_file_dest
)
LOOP
IF r.pct > 80
THEN -- Send alert or log warning
DBMS_OUTPUT.PUT_LINE(''FRA at '' || r.pct || ''%'');
END IF;
END LOOP;
END;',
start_date => SYSTIMESTAMP,
repeat_interval => 'FREQ=HOURLY;INTERVAL=1',
enabled => TRUE
);
END; /Best Practices for Archive Log Management
Based on our experience managing enterprise databases, here are key recommendations:
| Practice | Recommendation |
|---|---|
| Archive Destination Size | Maintain at least 2-3 days of archive logs capacity |
| Backup Frequency | Backup archive logs every 15-30 minutes in high-transaction environments |
| Monitoring Threshold | Alert at 70% usage, critical at 85% |
| RMAN Retention Policy | Configure automatic deletion of backed-up archive logs |
| Multiple Destinations | Use LOG_ARCHIVE_DEST_2 as failover destination |
Conclusion
ORA-00257 is a critical error that requires immediate attention, but with proper diagnosis and the right approach, it can be resolved quickly. The key is understanding that this error is Oracle’s protective mechanism preventing data loss when archive logs cannot be written.
Remember these key points:
• Always connect as SYSDBA when this error occurs
* Use RMAN for safe archive log deletion
* Implement proactive monitoring to prevent recurrence
* Maintain adequate space in your archive destinations
For related Oracle database administration topics, check our guides on Enabling Archive Log Mode in Oracle 19c and Oracle ASM Configuration Best Practices.
Have you encountered ORA-00257 in your environment? Share your experience and any additional tips in the comments below!