It is suggested you read through the article to familiarize yourself with the general process before you begin.
For most server platforms, you can upgrade your server to one with more resources. If you can no longer upgrade your server any further, or simply want to migrate your server to a new or different platform, you will have to order a new server from the 1&1 Order Site and checkout using your existing Customer ID and password.
You may have to re-image your new server to a different operating system if the server was not already set up using the operating system you require. Since you are using Plesk to manage your current server, you should choose a comparable operating system that includes Plesk for the new server.
Informing your site visitors ahead of time that you will be performing a migration to a new server will allow them to prepare for the fact that the site may not be accessible or may not function as expected during the timeframe chosen for the migration. Try to inform your site visitors as far in advance as possible.
Before you start your migration, you will want to have a complete backup of all your vital data and configuration. Save a copy of this backup to another location not on the server. This way, if an issue should arise during your migration, or some data is unintentionally lost, you will still have a complete backup of your server. You can either do this manually, or using Plesk Backup Manager
The link above will take you to the Plesk documentation on migrating your all of your data and configuration in Plesk from your current server to a new server. The page above offers various methods of migration depending on your scenario, such as transferring your data using the Plesk Migration & Transfer Manager, as well as best practices for migrating Plesk for Linux and Plesk for Windows.
Even though you have not moved your domains to the new server yet, you can still check to see if your website is running properly. Use the preview function to view each of your websites in Plesk to make sure that they appear to be loading properly. Plesk will use a special URL to preview the website on the new server instead of using the domain name.
Take note of all subdomains and any special DNS settings of domains and subdomains before making any changes to your domains.
To fully make the transistion to the new server, you will have to move your domains to the package or contract of the new server. Before doing this, you should first "point" your domain(s) to the new server's IP address(es). Setting your domain(s) to use the IP address(es) of the new server will force the domain to load the website files from the new server without actually performing the domain transfer yet.
If there is some issue with the website when loading from the new server, you can always revert the settings for the domain and point back to your current server until you can address the issue on the new server. You can either use the Plesk interface on the new server to find out the new IP address assigned to each domain, or you can use one of the commands below to get an output of all domains and the IP each is using:
After you know which IP address is being used for each domain on the new server, simply Change the Domain's IP Address in your 1&1 Control Panel. It is suggested to only make this change for 1 domain at a time. After making the change, load the domain in your browser to make sure that the website is loading properly from the new server before continuing with the other domains.
Once you have pointed your domain(s) to the new IP addresses and verified that they work properly, you can now fully transfer your domains to the new server package. Use the following Help Articles to walk you through the process of transferring your domain:
If your e-mail accounts were created and managed in Plesk, you most likely don't need to migrate your accounts as they should have transferred earlier in the migration process with all other data and configuration.
If your e-mail accounts were created and managed in the 1&1 Control Panel, you will have to do all of the following in the given order:
Any data or files that may have been saved to a custom location by the administrator user, root user, or any other user who was logged in through Remote Desktop or SSH should be considered, searched for and also moved if necessary.