Why so much inactive RAM ?

[jigsb007]

hello all,

i have noticed since i upgraded my 13" MB C2D to 8 GB ram, if i see always more then 4 GB of inactive ram ?

is there some problem in my memory ? i have recently upgraded to 8 GB.

 

[simsaladimbamba]

You have more RAM, thus more space to store the information in the "inactive" section, nothing to be worried about.

Inactive RAM:

This information is in RAM but it is not actively being used, it was recently used.

For example, if you've been using Mail and then quit it, the RAM that Mail was using is marked as Inactive memory. Inactive memory is available for use by another application, just like Free memory. However, if you open Mail before its Inactive memory is used by a different application, Mail will open quicker because its Inactive memory is converted to Active memory, instead of loading it from the slower drive.

from Using Activity Monitor to read System Memory and determine how much RAM is being used

 

[geoffreak]

From this article:

Free memory
As one might expect, this is the RAM that is sitting there with nothing to do. It is completely free for the system to use when needed.

Wired memory
Critical information stored in RAM by the system, its kernel, and some key application components. This stuff is basically frozen – it allocates its space and never moves to the hard drive or gets replaced with user-level data when RAM becomes scarce. An interesting thing to note about wired memory is that it scales based on how much total system memory is installed. For example, a Mac with 1GB of RAM may show 400MB of wired memory, while a Mac with 4GB of RAM may use 700MB. The more memory you have, the more your Mac wants to use it!

Active memory
Information currently in use or very recently used. If you’ve got Safari, GarageBand, iTunes, and Photoshop all going at the same time, your active memory is likely fairly high. Quit one or two of these applications and active memory will shrink. But not all of it will go straight back to free memory… some goes to the next category.

Inactive memory
One of the great things about Mac OS X’s memory management system is that it never stops working for you. Inactive memory is basically a handy storage space for convenient access to your most used tools. Let’s say you were working in iPhoto and decide to quit it. Some of the information that was stored in active memory by this application will be moved to inactive memory. This way, when you open iPhoto next time it will load up faster than before. Why? Because the computer is not reading everything from its slow hard drive again. I just ran a quick test myself to illustrate this point: After a system restart, I opened iPhoto and it took 3 Dock icon bounces to launch. I quit iPhoto, did some other stuff, and came back to it a few minutes later. This time it launched in 1 bounce.