~ Meghan Stewart | Support Escalation Engineer
When you are re-indexing the Configuration Manager database either through the built in Maintenance task or in SQL Server Management Studio, you may notice that your Replication Link will temporarily go into a degraded or failed state during this process.
This occurs because when you run a reindex on the database tables they are blocked and we cannot write to them. It is an offline operation and is fundamental to how DBCC REINDEX functions (see http://technet.microsoft.com/en-us/library/ms181671.aspx). In order for a sync on a replication group to be considered successful, we have to actually be able to process the data that the site received, meaning that during this re-indexing process, links can bounce from degraded to failed to active and back again. Depending on how much data is being replicated between the sites, the amount of time to go from a failed state to active will vary from environment to environment.
If this is an issue for you, note that the Replication Link itself has a set of thresholds that you can modify to adjust when the link goes into a degraded state or when it goes into a failed state. To see these thresholds, highlight the link under Database Replication then right-click and select Link Properties. Under the Alerts tab there are thresholds for setting the link to degraded or failed. By default these are set to 12 and 24 respectively and being able to set these thresholds is new in ConfigMgr 2012 Service Pack 1 (SP1).
The interesting thing to note about this is that in that Link there are multiple replication groups. They are broken up into two types: global data and site data. Global data attempts to sync every one minute whereas site date is every five minutes. Hit the threshold of 12 failures and you go degraded. Hit 24 and you are failed.
IMPORTANT If you choose to change these values, great care should be taken since the higher the value the longer it will take you to be notified of a problem. When choosing to increase or decrease the value, increment or decrement by 1 and monitor the link closely before making another change to it.
Meghan Stewart | Support Escalation Engineer | Microsoft GBS Management and Security Division
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The Forefront Endpoint Protection blog : http://blogs.technet.com/b/clientsecurity/
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The Forefront TMG blog: http://blogs.technet.com/b/isablog/
The Forefront UAG blog: http://blogs.technet.com/b/edgeaccessblog/