We have set up DAG monitoring scripts for one of our customers which tell us the status of all the mailbox copies and we noticed that one of the database copies had been stuck in a status of “Crawling” for over a day.
To rectify this problem we did the following:
1. Log onto the affected server and open up services.
2. Restart the “Microsoft Exchange Search Indexer” service:
3. Run the following PowerShell command in EMC:
Update-MailboxDatabaseCopy –Identity DATABASE\SERVER –CatalogOnly
This will update the search index of the database and then you can run the following command to ensure that the database index is now healthy:
Get-MailboxDatabaseCopyStatus -Identity DATABASE\SERVER
Cheers
Paul
本文来自：http://support.risualblogs.com/blog/2011/12/22/exchange-2010-content-index-state-crawling/