My steps
• I modified existing CSS file in the solution
• Deployed the solution. I saw the file was deleted and updated as new in the Style Library. I saw the date and time as new.
• I checked the pagelayout which uses the CSS did not effect
• I saw the CSS file copy never was updated with my changes.
o I downloaded and saw the copy… no change
o I tried looking in SPD there were no my change
Finally I saw that there is a BLOB CACHE which keeps the copy of the file. The blob cache is defined in the web.config file. This settings needs to be deleted. After that I was able to see the CSS file updating as I deploy the solution.
References:
http://social.technet.microsoft.com/Forums/en-NZ/sharepoint2010customization/thread/baa6e3b6-8f52-4755-8563-78fb29f51484
http://pravahaminfo.blogspot.com/2010/11/configuring-blob-caching-for-sharepoint.html
http://blogs.msdn.com/b/nehajain/archive/2009/05/25/how-to-automatically-reset-clear-the-blob-cache-disk-cache-programmatically.aspx