(this article is under development)
It is important to test the update process in a test environment. Test environment must be as much as possible similar to production.
Applying SharePoint updates to a server farm
Safest update method
The safest method to update a SharePoint farm is to take the entire farm offline, update all servers, and then bring the farm back online. This method requires a maintenance window that might not be practical for all organizations.
High availability updating
High availability updating involves more planning, testing, and coordination. The general outline for the process includes the following steps.