Question : ideal RAM for SQL server

Is there a specific way/formula to estimate how much RAM would benefit a SQL Server -like *how much of data is not able to be cached now, because of lack of memory?
*PerfMon counters to indicate how much extra memory would be helpful or ideal
*Can profiler be helpful for this?
*Can database size be related in any small way to the amount of RAM that would be needed.
etc

Specifically, I am thinking of a server with 8GB Ram (6 for SQL), 200 users, 8 xeon processors, but disk response is 45ms. the main database on this server is 60GB, and there is also a replica of the same for reporting.

Thanks

Answer : ideal RAM for SQL server

Determining the amount of RAM to allocate to SQL Server is not a science  it is more of
an art. One suggestion is to use the following rules-of-thumb:
" Reserve 1-2 GB of RAM for Microsoft Windows Server, ProHelp® EPM, and
other software programs, if the computer has more than 3 GB of RAM.
" Allocate all remaining RAM to SQL Server.
" Never allocate less then 1 GB of RAM to SQL Server.
Consider the following examples:
Assume system #1 has the minimum recommended amount of RAM  2 GB. Using the
rules above, you might allocate 1 GB of RAM for SQL Server and leave the remaining 1
GB unallocated (for use by other processes).
Assume system #2 has 4 Gig of RAM. Using the rules above, you might allocate 2 GB
of RAM to SQL Server and leave the remaining 2 GB unallocated.
Assume system #3 has 1 GB of RAM. You should upgrade the computer immediately!



So in short: put in 8GB in your case allocate what you need to SQL and check the performance counters, add more if needed.  All depends on the database and how it is designed, there is no straight rule for this.