I am developing a new website and would like to preserve the old website at a subdomain. (The old website has a lot of content which is useful enough not to just remove completely, but not valuable enough to 'convert' over to the new site.) Ideally the new site would be site.com and the old site would be archive.site.com (or site.com/archive - I can't tell if there's any reason to differentiate?)
Should I do something like a 301 redirect for either:
a) the main pages which existed on the old site and will exist on the new one (say site.com/events) b) to tell search engines that the page/result they had cached is no longer at site.com but archive.site.com
Initially I thought a 301 redirect from site.com to archive.site.com would work, but this would fail on pages that also exist on site.com.
Am I missing something? Or should I just use robots.txt to block search engines from caching the content at archive.site.com and just lose the SEO for all the old, archived content?