SharePoint Search functionality

Sometimes, SharePoint Search functionality doesn't work due to issues like error in Propagation Status in Search Administration such as query Server not responding.

Click  on the below link for solution.
http://venugopalareddy.blogspot.com/2014/10/query-server-is-not-responding-and.html


Also we need to clear the config cache on all servers.

This is a summary of the actions:

• Stop the “SharePoint 2010 Timer” service.

• There are loads of XML files that can be found in the folder "C:\ProgramData\Microsoft\SharePoint\Config\". Note there seems to  be folder(s) under Config which has a GUID. 

• Do not delete the folder(s) with GUID. 
• Delete all the XML files in the GUID folder. 
• Do not delete 'cache.ini' file.

• Edit the "cache.ini" file, setting the content to "1" (without the double-quotes). This indicates that all cache settings need to be refreshed. Eventually this value gets automatically updated to another number when the cache is repopulated.

• Start the “SharePoint 2010 Timer” service.

We need to perform the above steps on Index, Search, WFE(s) and App(s) servers in order.

Based on your SharePoint Usage, it is better to do this activity every 6 months.

For SP 2010 and 2013 >> https://spcachecleaner.codeplex.com/