With the ever-increasing demand for availability and business continuity, organizations often require the flexibility to move their critical SQL Server databases. Reasons for moving databases can range from maintenance to disaster recovery to capacity to performance management between different arrays where another array could be faster. ActiveCluster can step in as a reliable, real-time storage replication and failover solution that simplifies the database migration process.
ActiveCluster facilitates seamless and secure migration of SQL Server databases across sites or arrays located on the same site or across sites. It streamlines the migration process, reduces downtime, and ensures that critical SQL Server databases remain accessible and responsive during the migration process
When migrating data using ActiveCluster, a carefully planned phased approach can help ensure a smooth and efficient transition.
Non-disruptive Storage Migration Between FlashArrays
Proceed through the following stages to execute a successful storage migration from one array to another.
Start with a thorough assessment of the SQL Server database migration requirements, and then plan the migration process, including the source and target arrays, data replication, and failover procedures.
Ensure that the SQL Server database environment, including the source and target sites, meets the hardware and software requirements for ActiveCluster.
Ensure that all SQL Server workloads and applications can connect to the new array and that performance remains within acceptable parameters.
Configure ActiveCluster by connecting the arrays and setting up synchronous replication to have the SQL Server database replicated to the target array. Refer to the Configuring and Managing ActiveCluster section of this document for detailed steps on how to configure ActiveCluster.
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Set up ActiveCluster on the source and target arrays.
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Configure the necessary synchronous replication relationship between the sites or arrays to ensure real-time data replication.
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Configure the SQL Server host to have uniform access to both arrays. Be sure to configure MPIO.
Perform comprehensive testing to validate the migration process and the failover mechanisms by disabling the paths to the source array and validating data availability from the target array.
Test data accessibility and the responsiveness of the array at the target site.
When ready to migrate, initiate the failover from the source to the target site or array. The failover process is as simple as removing the paths of the source array from the SQL Server hosts. This ensures minimal downtime.
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Un-stretch the pod.
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Remove SQL Server hosts from Array A paths.
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Remove synchronous replication between the arrays.
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The SQL Server hosts can now access the database from Array B.
After the migration is complete, verify the integrity of the SQL Server database on the target site to ensure that data remains consistent and accessible.
Ensuring Consistency and Availability During Migration
Maintaining data consistency and ensuring continuous availability are critical factors during SQL Server database migrations using ActiveCluster. The following best practices can help ensure that these goals are achieved; by following these steps, you can maintain data consistency and availability throughout the migration process, minimizing downtime and preventing data loss during the transition between storage arrays.
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ActiveCluster synchronous replication ensures that all data changes are immediately written to both the source and target arrays before being acknowledged. This helps ensure that the data is consistent across both arrays throughout the migration process.
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It's essential to monitor the replication status closely before, during, and after the migration to confirm that data is in sync. This can be done by regularly checking the health of the replication link and ensuring no replication lag exists.
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During the migration, ActiveCluster uses the Pure1 mediator to maintain quorum and avoid split-brain scenarios. It is vital to ensure the witness is operational and reachable by both arrays.
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Monitor the connections of SQL Server hosts to the arrays to ensure they maintain a stable and consistent state, especially if failover is triggered.
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Before executing the migration, thoroughly test the failover process. During testing, simulate failure conditions by disabling paths to the source array and validating that the SQL Server hosts can seamlessly access the data from the target array.
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Test data consistency by querying the database on both arrays during replication to ensure that no data loss or corruption occurs. Ensure that the SQL Server high-availability features, such as SQL Server Always On Failover Cluster Instances, are configured correctly to manage failover without data loss.
Ensure that multipathing is configured for SQL Server hosts. MPIO ensures that SQL Server hosts maintain continuous access to both arrays in case one path fails. This redundancy ensures that data access remains uninterrupted during storage migration.
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After the migration and failover are complete, thoroughly validate the data on the target array. Run consistency checks on SQL Server (for example, using DBCC CHECKDB) to confirm that no data corruption occurred during migration. This step is crucial to ensure that data integrity is maintained.
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Ensure that all SQL Server workloads and applications can connect to the new array and that performance remains within acceptable parameters.
Additional Considerations
When performing a storage migration for SQL Server using ActiveCluster, there are several additional factors to consider in order to help ensure a smooth and efficient process. These considerations include the types of disks being used, their compatibility, and their performance implications.