When you need to migrate a ten year old website with 350+ pages of detailed content from one domain to another, you expect to run into difficulties. Some of the things that can go wrong are:
There are some strategies and observations that I can share with you here, based on my recent experiences. Let us take each point from the list above in turn.
The content on my site falls very much into the "long tail" of Internet traffic: lots of little bursts of traffic to many obscure articles, resulting in decent traffic overall.
The articles I publish that get the most attention tend to be technical, and people tend to enter and exist the site on the same page: basically they Google a technical query, and find the answer they were looking for on my site either via the Google search results pages directly, or via a post on another technical website that links to mine. All of those external links need to be handled with 301 re-directs (I wrote about this before). Once these re-directs are in place, the happy flow now looks like this:
This set-up is working very well for me so far, and as a result I will leave the old domain with the re-direct code running for the foreseeable future, given that links on the web tend to update slowly.
In many instances, the internal links in my content were broken. This was due to a number of factors, but mainly due to the fact that I changed the article URLs to a more flexible pattern. Where one article links to another article internally, these links were broken.
There is no sure way to fix these broken links other than manual review of content, and these efforts are still on-going.
Google loves 301 re-directs, and I can see the Google bot all over my logs, happily following the re-directs from my old content URLs to the new ones (the bot obeys the 301 re-directs just like a regular user's browser does). I have also set up a new sitemap.xml file (actually this is auto-generated here), and submitted that to Google via it's Webmaster Tools application. So far, so good.
Once I put the 301 re-directs in place, my traffic simply shifted from the old domain to the new. The traffic level has remained constant since the migration (so far).
Given that most of the traffic I get is organic search traffic from Google (~80%), all of my eggs are firmly in one basket. So far Google has not penalized me (and I have followed their guidelines on migration), but it is early days.
Nobody really knows for sure how important Google's page rank score is in terms of affected search traffic, however for the new domain I have a lower rank than the old domain. This makes perfect sense, as one of the flags that affects the authority of a domain when calculating page rank is thought to be the age of the domain.
I will keep an eye on page rank to see if any of it transfers to the new domain from the old, but so far the lower rank has not impacted on organic traffic levels from Google.