We will be modifying a SQL Deployment in our Hosted Environment. We have a solution which is currently configured to use one Application (and not SQL) System Database (which holds Security and System Level Configurations for our Application) and numerous independent Company Databases, each used by different users (originating from independent Organizations hosted in our Environment). We will be changing this deployment, after which each Organization will have its own System Database (instead of using a unique one for all Organizations). Thus, each Company Database will now have an associated Application specific System Database.
To summarize, before the deployment let us suppose that a Server had 100 Company Databases and one System Database, it will now have 100 Company Databases, plus 100 System Databases. Thus, the number of Databases will have doubled. Meanwhile, the number of transactions on the SQL Server will be identical. As an example, upon logging into a Company Database, a user will log into its associated System Database first in order to verify its Application specific Security Role for instance, instead of accessing the shared System Database as before. Hence, the Number of transactions launched against the System Databases will remain the same (as when there were only one of them), but the number of Databases will double.
Considering that the Number of Transactions will remain the same, but that the Number of Databases on the SQL Server Instance will double, how should we determine how much more Memory should we be adding (if any) to the Server?