Well, first things first, don’t PANIC!
Arm yourself with the following command
dfsrdiag replicationstate,look at the Windows Event Logs and DFS-R Debug logs located in C:\Windows\Debug.
They provide a wealth information.
Just as a reminder for myself I am going to include some resources below. Might come back and expand on them another time.
1. Checking for backlogs:
dfsrdiag backlog /rgname:rgroup_name /rfname:folder_name /sendingmember:sending_server
2. Setting verbose logging for DFSR logs:
wmic /namespace:\\root\microsoftdfs path dfsrmachineconfig set debuglogseverity=5
3. Translate GUID into file names. DFSR usus GUID to identify replicated files:
dfsrdiag guid2name /guid:guid_identifier /rgname:group_name
4. Getting the GUID’s of replicated folders:
wmic /namespace:\\root\microsoftdfs path dfsrreplicatedfolderconfig get replicatedfolderguid,replicatedfoldername
5. What is DFSR currently up to? – https://blogs.technet.microsoft.com/filecab/2009/05/28/dfsrdiag-exe-replicationstate-whats-dfsr-up-to/
6. Useful succint DFSR Troubleshooting notes with EventId’s – https://adminspeak.wordpress.com/tag/dfs-event-id-2212/
7. DFSR Event ID 2212 – https://support.microsoft.com/en-us/kb/977518
8. Understanding DFSR Dirty (Unexpected) File Recovery – https://blogs.technet.microsoft.com/filecab/2012/07/23/understanding-dfsr-dirty-unexpected-shutdown-recovery/
9. Understanding DFSR Debug logs. A great 21-part series on DFSR and Debug logs. Part 1 – https://blogs.technet.microsoft.com/askds/2009/03/23/understanding-dfsr-debug-logging-part-1-logging-levels-log-format-guids/