No Transaction Logs Truncated After Backup of Exchange DAG Passive Node 

This article is specific to a scenario where all of the following are true:

• Microsoft Exchange transaction logs are not truncated after the backup completes.
• The Microsoft Exchange VSS writer reports zero databases in its metadata on the passive node.
• The Microsoft Exchange Replication service VSS writer is disabled, and is not present in the list of VSS writers on any of the nodes, active or passive.

The Microsoft Exchange VSS writer must be enabled for Veeam to notify it to perform truncation.

The Exchange VSS writer is enabled by default. However, other legacy backup software may have required it to be manually disabled.

Ensure that the EnableVSSWriter registry value is set to 1 within the HKEY_LOCAL_MACHINE\Software\Microsoft\ExchangeServer\v15\Replay\Parameters registry key, then restart the Microsoft Exchange Replication service.