20 Common Ops Failures and How to Diagnose & Fix Them

1. Server Inaccessibility

Symptom: The server cannot be accessed over the network.

Diagnostic steps:

Check whether the server’s network connection is operational.

Verify that the server’s IP address and port configuration are correct.

Inspect firewall and security‑group rules to ensure they allow external access.

Remediation:

Reconfigure network settings to restore connectivity.

Adjust IP address and port settings to match incoming requests.

Modify firewall or security‑group rules to open the required ports.

2. Database Connection Failure

Symptom: Applications cannot connect to the database.

Diagnostic steps:

Confirm that the database service is running.

Check that the connection string is correct.

Examine network connectivity and firewall settings for the database server.

Remediation:

Restart the database service.

Correct any errors in the connection string.

Configure network and firewall rules to permit application access.

3. Disk Space Exhaustion

Symptom: Disk space on the server is critically low, affecting performance.

Diagnostic steps:

Run df -h to view usage of each partition.

Identify files or directories consuming large amounts of space.

Remediation:

Delete unnecessary temporary or log files.

Move or purge long‑unused data.

Consider expanding storage capacity or optimizing storage policies.

4. High CPU Utilization

Symptom: CPU usage remains high for extended periods, causing slow system response.

Diagnostic steps:

Use top or htop to view current CPU usage.

Identify processes that consume excessive CPU resources.

Remediation:

Optimize or refactor CPU‑intensive processes (e.g., improve algorithms, reduce unnecessary computation).

Upgrade hardware to improve CPU performance.

Apply load‑balancing techniques to distribute CPU load.

5. Memory Leak

Symptom: Server memory usage continuously grows until exhaustion.

Diagnostic steps:

Run free -m to check memory consumption.

Use tools such as valgrind to detect leaks.

Remediation:

Fix the code that causes the leak.

Increase server memory or improve memory‑management strategies.

6. High Network Latency

Symptom: Network latency is high, slowing data transfer.

Diagnostic steps:

Run ping to measure latency.

Analyze network topology to locate bottlenecks.

Remediation:

Optimize network configuration (adjust router/switch settings).

Upgrade network hardware to increase bandwidth.

7. DNS Resolution Failure

Symptom: Domain names cannot be resolved, preventing access to network resources.

Diagnostic steps:

Use nslookup or dig to test DNS.

Check DNS server configuration and status.

Remediation:

Repair or replace the faulty DNS server.

Configure secondary DNS servers for redundancy.

8. Application Service Crash

Symptom: The application service stops unexpectedly and cannot serve requests.

Diagnostic steps:

Examine service log files to determine the cause of the crash.

Verify that system resources (CPU, memory) are sufficient.

Remediation:

Fix the underlying error indicated in the logs.

Optimize resource allocation to keep the service running.

9. File‑System Corruption

Symptom: File‑system errors cause abnormal data access.

Diagnostic steps:

Run fsck to check file‑system integrity.

Investigate possible causes of corruption.

Remediation:

Use fsck to repair the damaged file‑system.

Strengthen backup and recovery strategies to prevent data loss.

10. System Update Failure

Symptom: Errors occur during system updates, causing the update to fail.

Diagnostic steps:

Review update logs to identify the failure reason.

Check that network connectivity and storage space are adequate.

Remediation:

Adjust update settings based on log information.

Ensure a stable network and sufficient storage.

Attempt manual update or roll back to a previous version.

11. Permission Misconfiguration

Symptom: Users cannot access or modify specific resources.

Diagnostic steps:

Inspect file and directory permission settings.

Confirm that users belong to the correct groups.

Remediation:

Correct permission settings to grant appropriate access.

Add users to the proper groups.

12. Web‑Server Configuration Error

Symptom: The web server returns errors or fails to handle requests correctly.

Diagnostic steps:

Check configuration files (e.g., httpd.conf for Apache, nginx.conf for Nginx).

Review web‑server logs for error messages.

Remediation:

Adjust settings according to errors found in configs or logs.

Restart the web server to apply changes.

13. Email Service Failure

Symptom: Emails cannot be sent or received.

Diagnostic steps:

Check the mail server’s operational status and logs.

Verify network connectivity and DNS configuration for the mail server.

Remediation:

Fix the mail server issue or restart the service.

Configure correct network and DNS settings to ensure smooth mail flow.

14. Backup Failure

Symptom: Backup jobs abort with errors, leaving data unprotected.

Diagnostic steps:

Inspect backup logs to determine why they failed.

Check the health and capacity of backup storage devices.

Remediation:

Adjust backup configuration based on log details.

Ensure storage devices are healthy and have enough space.

Rerun the backup or restore from a previous snapshot.

15. Load‑Balancing Imbalance

Symptom: The load balancer does not distribute requests evenly across back‑end servers.

Diagnostic steps:

Review load‑balancer configuration and health status.

Analyze back‑end server load to pinpoint the cause of imbalance.

Remediation:

Adjust load‑balancer settings to achieve even distribution.

Optimize back‑end server performance.

16. Firewall Rule Error

Symptom: Incorrect firewall rules block access to certain resources or services.

Diagnostic steps:

Inspect current firewall rule set.

Determine which resources or services are affected.

Remediation:

Modify rules to allow required traffic.

Regularly review and update firewall policies.

17. SSH Connection Failure

Symptom: Unable to establish an SSH session to a remote server.

Diagnostic steps:

Check that the SSH service is running.

Verify the SSH port and IP address configuration.

Ensure firewall rules permit SSH traffic.

Remediation:

Restart the SSH service.

Correct any misconfiguration of port or IP.

Adjust firewall rules to allow SSH connections.

18. Database Performance Degradation

Symptom: Queries run slower and response times increase.

Diagnostic steps:

Use performance analysis tools (e.g., MySQL EXPLAIN) to examine query plans.

Review indexes and table structures for inefficiencies.

Remediation:

Optimize query statements to reduce unnecessary work.

Create or adjust indexes to improve lookup speed.

Refactor table design (partitioning, archiving old data).

19. Application Dependency Issues

Symptom: The application fails to start, reporting missing dependencies.

Diagnostic steps:

Inspect the application’s dependency list.

Confirm that required dependencies are installed and correctly configured.

Remediation:

Install any missing dependencies.

Set appropriate environment variables and paths.

Ensure dependency versions are compatible with the application.

20. Virtual‑Machine Fault

Symptom: The VM fails to start or behaves erratically.

Diagnostic steps:

Examine VM configuration files and logs.

Assess allocated hardware resources and OS health.

Remediation:

Fix configuration or OS issues based on log analysis.

Adjust resource allocation (CPU, memory, storage).

Restart the VM or revert to a known‑good snapshot.