What you need to know
When is a managed cross-region incremental snapshot copy ready for restoration?
Potentially affected
Operators copying Azure managed-disk incremental snapshots between regions using the managed copy process.
DSE recommendation
Track each disk's snapshot sequence and retain its source until the target copy reaches the documented completion state.
Source facts
Microsoft’s managed cross-region process copies changes since the previous snapshot in the target region. For a particular disk, only one incremental snapshot can be copied at a time, and copies must follow creation order. The source snapshot must not be deleted during copying. The target’s CompletionPercent must reach 100 before it can restore a disk or provide a SAS download URI. Microsoft Learn.
Applicability
Apply this review to the managed incremental-snapshot copy workflow, not a full snapshot or a separately implemented block-difference copier. Identify the disk, source snapshots, target region, and intended recovery point before scheduling the sequence. Keep the copy’s completion criteria separate from application recovery acceptance.
DSE recommendation
Track each disk’s snapshot sequence and retain its source until the target copy reaches the documented completion state. Give the operator a queue that records creation order, active copy, and next eligible snapshot. Require an explicit check before cleanup so a retention task does not remove a source that is still being copied. Assign responsibility for a stalled sequence rather than silently starting a later snapshot.
Verification
Record the target snapshot identifier and observed CompletionPercent for each completed transfer. In an approved recovery test, use the completed target to restore a disk and compare its contents with the selected recovery point. Record transfer completion and restoration validation as separate results. Investigate an unexpected order, incomplete target, or content mismatch before accepting the regional copy as usable recovery material.
Official references
Microsoft Learn: Copy an incremental snapshot to a new region. Source reviewed September 9, 2026.
Review the official source
Copy a snapshot to a new region - Azure Virtual Machines | Microsoft Learn · Verified September 9, 2026
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