Happens when a DC is put back to an earlier state in a way Microsoft does not support, for example by restoring an old disk image or snapshot; other DCs then disregard new updates from it and replication becomes inconsistent.
Read more: Microsoft Learn
In the Ultra Transcenders books
Each book explains USN rollback in context, with comparison tables and the common traps.
Terms in this definition
- EARLIER
Within nested DAX row contexts, lets an inner calculation read a column as it stood in an outer pass; EARLIEST jumps to the outermost. Most people now use variables, which read more clearly.
- State
A parameter in OAuth that carries custom data through the authorisation flow and back, as with the "Support state parameter" option in APIM.
- snapshot
Captures a VM's disk state, power state, settings and, if requested, memory at a moment in time, using one delta disk per virtual disk. Snapshots should not be relied on as backups.
Related terms
- Invocation ID
Changes after a restore or a VM-GenerationID change to protect against USN rollback; it identifies the database instance on a DC.
- VM-Generation ID
A value provided by Hyper-V and other compatible hypervisors that changes whenever a VM is copied or a snapshot is applied, so a virtualised DC can notice and guard against USN rollback.