I have a simple little network with 3 AD servers in 2 sites. Site A has Win2k3 SP2 and Win2k SP4 servers, site B has a single Win2k3 SP2 server. All have been in place for at least 3 years now.

Just last week I started getting Event 2089 "not backed up" warnings (example below) on both of the win2k3 servers. I understand what the message means, no need to send me links to the technet article explaining it. I'll improve my backups.

What I'm more curious about is why did I just start getting this message now? Why haven't I been getting it for the past 3 years?!?

Perhaps this is related: I recently decommissioned a few other sites and AD controllers (there used to be 3 more sites, each with their own controller). Don't worry, I did proper DCpromo exercises and made sure we didn't lose anything. But would shutting those down possibly be related to why I get this error now?

This won't keep me awake at night but I am curious as to what changed...

Event Type: Warning
Event Source:   NTDS Replication
Event Category: Backup 
Event ID:   2089
Date:       3/28/2010
Time:       9:25:27 AM
User:       NT AUTHORITY\ANONYMOUS LOGON
Computer:   RedactedName
Description:
This directory partition has not been backed up since at least the following number of days. 

Directory partition: 
DC=MyDomain,DC=com 

'Backup latency interval' (days): 
30 

It is recommended that you take a backup as often as possible to recover from accidental loss of data. However if you haven't taken a backup since at least the 'backup latency interval' number of days, this message will be logged every day until a backup is taken. You can take a backup of any replica that holds this partition. 

By default the 'Backup latency interval' is set to half the 'Tombstone Lifetime Interval'. If you want to change the default 'Backup latency interval', you could do so by adding the following registry key. 

'Backup latency interval' (days) registry key: 
System\CurrentControlSet\Services\NTDS\Parameters\Backup Latency Threshold (days) 


For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.