Memory requirement most people don't understand

I think many people in the IT world will know what the memory requirement is. Actually what is the requirement for a system is considered enough? Let say, database software purchased require 256 MB of RAM. Is it mean you just need to install 256 MB RAM to the system so that it fulfill the software requirements? I think that is stupid decision.

Let take a look for a hard disk spaces requirement for that database. It may stated that it require 2 GB of free space. Does it mean you only need to purchase 2GB of hard disk? The answer is definitely “NO”. This is because you have to think of the other occurrences of software that will use that hard disk also. So the actual hard disk will take more than 2GB. Why? Windows it self is almost takes 2 GB of hard disk spaces. Other software such as Java (100 MB), Office (500 MB) and etc (1 GB). So the “concurrent” spaces require is about 5.6 GB. Add 20% for performance issue, the spaces you need for that system is roughly 6.5GB.

Now back to the memory case. We should consider the “concurrent” application that is running. Windows takes 128MB, Java takes 128MB and then the database takes 256MB. Total up would be 512 MB. So this is the way we calculate the total amount of RAM required for a system. Not blindly put the particular software requirement as a standard.