XFS memory recomendation?

["Assarsson, Emil" <Emil.Assarsson@xxxxxxxxxxxxxxxx>]

Hi,

Are there any recommendations about how much memory I need based on the size of 
the file system and/or amount of files?
For example: how much memory would be optimal for a 20TB file system with 
3000000 files? 

I guess it depends on the usage pattern?
Is there any way to make sure that the file allocation table stays in the 
memory?

Best regards
Emil Assarsson