What do you do if your database crashes and you need to quickly resolve the issues?

Error Logs: Start by checking the SQL Server error logs (errorlog and errorlog.n files) for any error messages or warnings leading up to the crash. Look for entries related to system shutdowns, unexpected terminations, or critical errors that may have triggered the crash.

Identify the nature and extent of the crash. Determine if it's a hardware failure, software issue, or some other cause. Evaluate the impact on data integrity and availability. Understand which parts of the database are affected.

we have different methods to bring back database to online. 1. if backup policy and BCP, Disaster recovery are in place, will use one of these and bring the database online. 2. if the setup. has log shipping . Will back secondary server online, with minimum data loss( depends up on the frequency of transaction log backups) 3. stop the sqlserver services. rename the log file (ldf file) and when u start it . it creates a new log file and it may comes online. run db consistency to checks to ensure the database is good in terms of health. 4. change the database mode to emergency and single user mode. try to repair with no data loss option. if this does not work try with repair with data loss option. Call need to take depends on datasensivity

System Health: Review system health logs, if available, to monitor system resource usage (CPU, memory, disk) leading up to the crash. Look for indications of resource exhaustion, high contention, or performance bottlenecks that could have contributed to the crash.

Verify the health of the underlying hardware. Check for any disk failures, memory issues, or CPU problems. Examine system logs and error messages to pinpoint the root cause of the crash. This may involve checking database-specific logs as well.

Transaction Log: Examine the transaction log (transaction log files, transaction log backups) to identify active transactions and logged changes at the time of the crash. Look for incomplete transactions, uncommitted changes, or transactions in a pending state that may need attention during recovery.

If you have recent backups, ensure they are accessible and up-to-date. Consider the type of backup (full, incremental, differential) and choose the most appropriate for restoration. If backups are unavailable or outdated, explore options for data recovery such as log file replay or transaction rollback.

Checkpoint logs provide information about checkpoint activities and recovery progress. Verify the last successful checkpoint and any ongoing recovery operations. Ensure that the database is in a consistent state and that recovery processes are completing successfully.

Depending on the type of crash and available backups, initiate the recovery process. This may involve restoring from backups, repairing corrupted data, or rebuilding indexes. Follow database vendor guidelines and best practices for recovery procedures. Use recovery modes like point-in-time recovery if applicable.

Perform database integrity checks using DBCC CHECKDB to identify and repair any corruption or inconsistency in the database files. Analyze the results of DBCC CHECKDB to determine the extent of damage and plan recovery actions accordingly.

Once the recovery process is completed, set up a testing environment to validate the restored data and functionality. Conduct thorough testing including data integrity checks, query performance tests, and application functionality testing.

Perform database integrity checks using DBCC CHECKDB to identify and repair any corruption or inconsistency in the database files. Analyze the results of DBCC CHECKDB to determine the extent of damage and plan recovery actions accordingly.

After restoring the database, monitor its performance and stability closely. Look for any signs of recurring issues or anomalies. Implement proactive monitoring tools and alerts to detect potential problems early.

By thoroughly examining these logs and gathering relevant information, you can diagnose the cause of the database crash, assess the extent of data loss or corruption, and formulate an effective recovery plan to restore the database to a consistent and operational state.

-The first thing is not to panic and keep cool. -I would go to the log straight away and analyze the errors. -Let the management know about this . Also, Let the user community know about the issue through helpdesk , assure them that the issue will be resolve and that they would be informed accordingly. -Choose a best recovery solution accordingly. -Apply any configuration change as per Change Management process . -Once the issue is fixed inform the management and user community. - Prepare and share and RCA accordingly.

Document the incident, including the cause, actions taken, and lessons learned. This will help improve your response in future incidents. Review your disaster recovery plan and make any necessary updates based on the lessons learned from the crash. Consider implementing redundant systems, clustering, or failover mechanisms to enhance database resilience and minimize downtime in the future.