Reset FAST Search Server for SharePoint (FS4SP) Index

First, need to reset the index in Central Administration / Application Management / Manage Service Applications, then click your FAST Search content SSA, then click Index Reset.

We are not done yet, we also need to manually clear the content from the content collection that our FAST Search Content Search Service Application feeds to. The default collection name is sp.

To clear a FAST Search Server 2010 for SharePoint content collection, log onto the server that hosts FAST Search Server 2010 for SharePoint and follow this procedure.

Clear the content collection

1. Verify that you meet the following minimum requirements: You are a member of the FASTSearchAdministrators local group on the computer where FAST Search Server 2010 for SharePoint is installed.
   
2. On the Start menu, click All Programs.
   
3. Click Microsoft FAST Search Server 2010 for SharePoint.
   
4. Click the Microsoft FAST Search Server 2010 for SharePoint shell.
   
5. At the Microsoft FAST Search Server 2010 for SharePoint shell command prompt, type the following command:
   Clear-FASTSearchContentCollection -Name
   Where:
   
   • is the content collection you are about to clear.
     
6. Wait for the command to finish. This may take some time.
   
   After all of above is finished, then we can start new crawls.