How do I size the target server and migration window?
Size the destination for the workload it will run and the temporary work needed during migration. Estimate the window from measured transfer and validation times, including the final consistency step. Matching the old server’s advertised specification is not enough if the workload or platform changes.
Before you start
- Current resource measurements, data size, change rate and a proposed destination.
Instructions
1. Check steady-state and temporary capacity
Compare CPU capability, memory, usable storage and network limits with actual peak demand. Allow room for staging files, database import work, indexes and logs. Check operating-system, architecture and database-version compatibility before assuming the same files can run unchanged.
2. Measure a representative transfer
Use an authorised rehearsal to measure effective transfer speed and destination write performance. Account for small-file overhead, encryption, checksumming and database export/import time where relevant. The raw network port speed is an upper bound, not an estimate of end-to-end migration throughput.
3. Budget the final window
Estimate the data that changes during the initial transfer and how it will be reconciled. Include write pauses, connection changes, application checks and time to stop or roll back before the agreed deadline. Schedule the move around the application’s business workload and staff availability.
Check the result
- The destination meets workload requirements and has adequate temporary working space.
- A rehearsal supports the proposed window and identifies the latest safe decision point.
Troubleshooting
- The final sync grows faster than it transfers
- Compare source change rate with effective transfer capacity. Reduce the change window, use a supported replication approach or plan an explicit write pause rather than assuming repeated copies will eventually converge.
Official references
Use the documentation for your installed version when a flag, service name or platform feature differs.