In some environments, the creation of top level sites (TLS) is strictly controlled such that IT Pros are the only folks who can create new TLS. Sometimes, in these environments, there is also a desire to map which database will host the new TLS.
You can determine which database will host the next TLS when it is created by using the Offline feature for the SharePoint databases. Databases in SharePoint can be set to either Ready or Offline. The Offline setting doesn’t take the database offline, instead it simply locks the database from accepting new TLS creations. Within existing site collections, you’re able to work with documents, create new sites, create new workspaces and continue to work normally across all functions. But you won’t be able to create new TLS in the database until it is set to Ready.
So, let’s assume you have 20 content databases associated with an individual virtual server and you want to ensure that certain TLS are created within specified databases. You’ll need to manually set all 20 databases to Offline and then when you’re ready to create a new TLS into a specific database, manually set the database to Ready, create the TLS, then reset the database to Offline.
Now, a couple of disclaimers. First, this is not an elegant solution, but it is doable. Secondly, if you merely want to round robin the creation of new TLS in SharePoint, then this is not a solution you need to implement. But if you need to specify into which database the next TLS will be created in a non-sequential order, then this is a good method to us.