You're faced with a database failure. How do you maintain data integrity during the restoration process?

?? Assess Damage: Begin by thoroughly evaluating the extent of the failure. Identify which data files or segments are compromised, and determine whether it’s a physical corruption (e.g., disk failure), logical corruption (e.g., data integrity issues), or a complete system crash. ??? Targeted Recovery: Once you've determined the scope, decide on the recovery method. For localized issues, restore only the affected parts of the database. If widespread damage is detected, consider a full restoration strategy.

The first step is understanding the nature and extent of the failure. Determine whether the issue is due to hardware failure, logical/data corruption or software issues. Check SQL Server error logs, system event logs, and application logs to gather information on what caused the failure. Use DBCC CHECKDB to evaluate the extent of database corruption, if applicable. This command checks the logical and physical integrity of all objects in the database and helps identify issues like corrupt pages or broken relationships.

By creating a "war room" with key participants involved, they can help determine the damage much quicker than you can as a DBA. The critical component of a "war room" is the participants and what disciplines they represent. Assign them tasks that are directly in their area of expertise and have them assess damages. Multiple people working on the problem makes the solution a lot easier to find and repair. The participants need to be seasoned people from Applications, Development, DBA, Systems and Operations.

Not only should you verify the backups are current and uncorrupted but you should also plan on having something go wrong with the backup and need to go to another level of recovery. I had a multi-level recovery plan in place that started with log files, database backup files, with multiple generations, and system backups that included the catalog, log, and intermediate files that would be required to facilitate a recovery. I practiced several recovery scenarios to make sure that when I needed them, I would be able to go back several levels if needed.

Esta tarea sin bien es correcta, no debe ser ejecutada cuando sucede algo, siempre debe de validar sus copias de seguridad diarias, cree planes de pruebas para validar que las copias que ha tomado estén en condiciones optimas, no confié plenamente en el proceso de backups, porque otro punto de fallo que puede comprometer su copia de seguridad es el almacenamiento donde esta se encuentra y por supuesto que si usa un aplicativo de tercero para la gestión debe de tener un constante seguimiento de su salud y actualizaciones.

Before initiating any recovery, it's essential to verify that your backups are usable. Ensure that you have recent full, differential, and transaction log backups. These should be validated to confirm they aren't corrupted. Use the RESTORE VERIFYONLY command to check the integrity of your backup files. Check how recent the backups are and whether they cover the period before the failure. Ensure you have access to all the required files (full, differential, transaction logs) for the restore process.

?? Backup Verification: Before proceeding with restoration, ensure your backups are both recent and intact. Check the logs for any signs of failure, and confirm that the backup files are accessible and complete. ??? Thorough Validation: If possible, test the backup by restoring it in a non-production environment to guarantee that the data is valid. Choose the most up-to-date and reliable backup set to minimize data loss and avoid potential complications during recovery.

With the damage assessed and backups verified, create a restoration plan. Based on the failure and backup availability, decide the point in time to which the database should be restored. This might be the latest backup or a specific point in time if transaction log backups are available. Decide whether to use a Full Restore, Differential Restore, or Point-in-Time Restore based on the available backups and the need to minimize data loss. The recovery model (Full, Bulk-Logged, or Simple) will influence your approach. If possible, implement a plan that balances minimizing downtime and ensuring data integrity. Restoring to a separate environment and using Log Shipping or Always On Availability Groups to sync back can help in some cases.

?? Restoration Plan: Create a step-by-step restoration strategy that prioritizes data integrity. This plan should detail the restoration of data files, transaction logs, and verification protocols post-restoration to ensure completeness. ? Minimize Downtime: Tailor the plan to reduce downtime by restoring critical components first. Include procedures to check data consistency and avoid accidental data overwrites. Also, communicate the timeline and potential impacts to the team and stakeholders, ensuring everyone is aligned.

To maintain data integrity during a database failure, implement a comprehensive restoration plan with both onsite standby and DR site options. Utilize onsite standby for quick recovery, ensuring minimal downtime, and DR site for major failures, providing a robust backup to ensure consistent, verified data restoration.

Execute the recovery process based on the plan you created. Begin by restoring the most recent full backup using the RESTORE DATABASE command with NORECOVERY to allow for additional differential or log restores. If applicable, restore the latest differential backup with NORECOVERY to ensure no additional log file restores are blocked. If you're using the Full recovery model and transaction log backups, apply them sequentially up to the failure point, using WITH NORECOVERY for each until the final log, which should be restored with WITH RECOVERY.

Most of the databases have logs and some timestamps just before failures. The key is that bring database to last backup stage and apply redo logs or recover from flashback area with latest key switch from control files etc. This way data integrity can be maintained in a production database.

To ensure predefined RTO and RPO goals during database restoration, validate data through backup integrity checks, transaction log reviews, and consistency validations. This ensures data is restored accurately, minimizing downtime and data loss while maintaining operational standards.

Once recovery is complete, validate the data integrity. Re-run DBCC CHECKDB to verify that the database integrity has been restored and that no lingering corruption remains. Ensure that the applications using the database can access the data correctly and perform as expected. Depending on the recovery model and backups used, confirm that no transactions are out of sequence or missing. If possible, cross-check critical data against known correct data points or previous snapshots to ensure no major data inconsistencies exist.