Psych barriers. Back in 2008, 16 gig was alot of memory. Now my PC has 16 and its easier to ask and easier to get 24 gig of server memory for 200 Gb PeopleSoft database.
Some storage admins think that SQL will use what ever memory is given it. That SQL would use 16Gb for an 8Gb database. I know this is not the case.
What is the real rule of thumb? Add memory till the performance curve flattens out ?