If you want to install Sage CRM to another Server and skip the creation of the database (if the CRM database already exist and in use in production the Setup will failed and Rollback).
This can be usefull if you want to transfer the CRM to another server or deploy a new CRM install in a Clustering Mode.
From a command prompt (cmd.exe) start the CRM Setup setup.exe with the option nodb
Have Fun deploying several Node !
Service Pack :
“There’s no need for the nodb option for Service packs. Yes service packs might update the metadata, but it doesn’t affect the database if you re-run the same patch more than once. ” From Sage Support Level 3