Overview
A transfer is constrained by its bottleneck. A 10 GbE link has a theoretical payload ceiling of roughly 1,250 MB/s before protocol and implementation overhead, but the storage devices may be much slower.
Engineering considerations
Large sequential transfers can approach storage throughput; small files can be dramatically slower because metadata operations and latency dominate. Encryption, snapshots, deduplication and concurrent workloads can also reduce effective throughput.
How to plan it
Measure the source and destination rather than assuming their interface speed is their sustained transfer speed. For network migrations, compare effective network throughput with both storage endpoints.
Design implications
Use the Storage Transfer Time Calculator for an initial duration and bottleneck estimate. Add operational margin for verification, retries and application downtime windows.