Cutover methodology
Several options for the methodology and configuration of systems are involved in the final cutover data migration.
Direct migration
You can directly migrate from the source production system to the target production system. This is the most straightforward method but may be prevented due to security or logistical reasons.
The source and target production systems are shut down through the cutover data migration process to prevent any changes from being made to the data.
Direct network connectivity between the source and target system is not a requirement for migrations with BMC Helix Data Manager.
While this method is the simplest and often the fastest method for the cutover data migration, it can be more laborious to compare data in the source and target systems if any post- or pre-data migration validation is required.
The cutover migration might be the first time that a data migration has been performed between these two systems. If this is the case, you should validate the connectivity and migration capabilities prior to the cutover weekend.
Mirroring the source
The source production database is copied to a staging database, typically hosted on the same database server as the production target database. The process of exporting and copying the source database adds an additional step and time to the overall cutover process, but may be desirable for security or logistical reasons.
The source and target production BMC Helix ITSM systems are shut down through the cutover data migration process to prevent any changes from being made to the data.
This approach has the additional benefit of providing a static data set that exactly reflects the state of the source system at the time of cutover. If the data is hosted on the same database server as the production target, this approach supports rapid and straightforward comparison and validation of data.
The cutover migration might be the first time that a data migration has been performed between the staging and production database. If this is the case, you should validate the connectivity and migration capabilities prior to the cutover weekend.
Mirroring the source and target
To prevent any changes being made to the data, the source and target production BMC Helix ITSM systems are shut down through the cutover data migration process. The source production database is copied to a staging database, typically within the data migration environment that has been used for the development and testing of the migration configuration. Simultaneously, the target production database is copied into the data migration target environment. The data is then migrated from the source staging database into the target data migration database. The success of the migration is validated prior to the target database being updated with a copy of the data migration target environment. The source and target production systems are shut down through the cutover data migration process to prevent any changes from being made to the data.
This is more complex approach to the cutover migration but has the following significant benefits:
- The target production system is not changed in any way until the data migration is validated. This provides a fast and safe rollback in the event of a critical failure.
- The cutover migration is performed in the same systems that have been used for all development and testing of the migration process. This significantly reduces the risk of unforeseen issues.
- The source and target data sets can be easily compared and validated in the dedicated data migration environment.
This approach adds two database copy operations into the cutover process:
- The copy from source and target database into the data migration environment
- The copy back from the data migration target to the production target database
This adds significant time to the overall cutover duration (dependent on data volumes, locations of the systems, and network performance).
Despite this overhead, this represents the lowest risk approach to consolidation with the best rollback capability.
