Website maintenance regularly requires content to be moved from a subdirectory to a sub domain or to a completely new domain – this can engage a bit of an effort but it has to be done with caution as you can permanently lose all the data.

To assist search engines to comprehend your new website structure it’s advised that you make your site to be more user friendly and adhere to the below guidelines:

  • It’s imperative to forward all users and bots that visit your old content location to the new content location by employing 301 redirects. To emphasize the rapport between these two locations, make it a point each old URL points to the new URL that hosts similar content. You can alternatively make use of cross domain canonicals for search engines that is if you can’t use 302 redirects.
  • See if you have both the new and the old location confirmed in the same Google Webmaster Tools account.
  • Make it a point that the new location is crawlable by Googlebot using the Fetch as Googlebot feature. It’s vital to make sure Google can actually access your content in the new location. Also make sure that the old URLs are not blocked by robots.txt disallow directive, such that the redirect or rel=canonical can be found.
  • If you have decided to change the URL structure of your site, make sure that it’s possible to navigate it without running into 404 error pages. Google Webmaster Tools can prove helpful in investigating potentially broken links. Just look for diagnostics>Crawl errors for your new site
  • Check your Sitemap and authenticate that it’s up to date
  • Upon setting up your 301 redirects, you can keep an eye on users to your 404 error pages to check that users are being redirected to new pages, and not accidentally ending up on broken URLs. When a user visits a 404 error page on your site, try to identify which URL they were trying to access, why this user was not redirected to new location of your content, and then make changes to your 301 redirect rules as appropriate
  • Have a look at the links to your site in Google Webmaster Tools and inform the important sites that link your content about your new location
  • If your site’s content is specific to a particular region you may want to double check the geotargeting preferences for your new site structure in Google Webmaster Tools.
  • As a general rule for thumb, you should avoid running two crawlable sites with completely or largely identical content without a 301 redirection or specifying a rel=”canonical”.
  • Finally, Google advise that you should not implement other major changes when you’re moving your content to a new location, like large scale content, URL structure, or navigational updates. Changing too much at once may confuse users and search engines.

Source: http://googlewebmastercentral.blogspot.com/2012/04/how-to-move-your-content-to-new.html