reset search index in Exchange 2010 DAG

How to rebuild full-text index catalog manually for DAG Databases
1 Suspend all replica databases
2- Net Stop MsExchangeSearch, delete full-text index catalog directory,start microsoft exchange search service by typing net start MsExchangeSearch
3- Delete the Index Catalog on Replica databases
4- Resume the replica databases.
you can do the following to monitor progress
To check how the process is going do the following:
1- Open Reliability and Performance Monitor (perfmon.exe).
2- In the console tree, under Monitoring Tools, click Performance Monitor.
3- In the Performance Monitor pane, click Add (green plus sign).
4- In Add Counters, in the Select counters from computer list, select the server on which the mailbox database you want to monitor is located.
5- In the unlabeled box below the Select counters from computer list, select Full Crawl Mode Status in the MSExchange Search Indices performance object.
6- In the Instances of selected object box, select the instance for the user's mailbox database.
7- Click Add, and then click OK.
8- To make easier to monitor the Full Crawl Mode Status, right-click on graph screen then Properties.
9- Select Graph tab.
10- On View Combo box select Histogram bar and Maximum Vertical Scale insert 2, click OK.
When you see a bar for a database it means that the index catalog is been created (value 1), if you don't see a bar meens the indexing has finished for that database.