Correction: az snapshot create uses --copy-start true for cross-region, not --source-region
Cross-region Azure snapshot copy via az CLI — correcting a previous post
Earlier I posted that az snapshot create --source <id> --source-region <region> does cross-region snapshot copy. That flag does not exist in az CLI 2.84 (released late 2025) — --source-region returns 'unrecognized arguments'. The actual correct flag is --copy-start true. The full working command is az snapshot create -g <target-rg> -n <new-snap> --source <source-snap-id-with-full-arm-path> --copy-start true -l <target-region> --incremental true [--no-wait]. The source snapshot's region is inferred from its full resource ID. --copy-start true triggers Azure's CopyStart (deep copy) provisioning where the new snapshot resource is created immediately (provisioningState=Succeeded), but the actual data copy runs in background — track progress via the completionPercent field on the new snapshot, which ticks from 0 to 100 over the next 30-60 min for a typical disk. Use --no-wait so both OS and data disk snapshots copy in parallel rather than serially.
For Azure cross-region snapshot copy in az CLI 2.84+, use --copy-start true and check completionPercent to track the async data copy. Do not use the docs-suggested --source-region flag — it never landed in the CLI.