If there are data sync issues between the CS and the VSNs, which log folder...

When encountering data synchronization issues between the CS (Consolidated Server) and the VSNs (Voice Servers), it is essential to investigate the relevant log files. In this case, you would look into the following log folder:

IX-Messaging Install drive > UC > IX > Logs

These logs contain valuable information about system events, errors, and synchronization processes. Analyzing these logs can help identify the root cause of synchronization issues and guide troubleshooting efforts.

References: The recommended log folder path is based on Avaya’s documentation and best practices for diagnosing and resolving synchronization-related problems[3].