Search Storage in SharePoint 2013

Search generates different kind of data while crawling , Following are the types of data

        1).Crawl data - is from where the index is built - this is stored on the SQL server. - The Crawl database stores the state of the crawled data and the crawl history.

 
       For SQL server sizing we only need to care about the crawl data.

* For  10 million items - 15GB DB, 2GB log

* For 100 million items - 110GB, 50GB log

currently we have one crawl database ,it can store up to 20 M items.

2) Link DB - The Link database stores the information that is extracted by the content processing component and the click through information.

* For 10 million items - 10GB DB, 0.1GB log

* For 100 million items - 100GB, 5GB log

3) Index - is where the search results are queried from - this is stored on the SharePoint servers.

       Default Index Location is : C:\Program Files\Microsoft Office Servers\15.0\Data\Office Server\Applications