Memory Allocation in Shared DB & IIS Environment In my use case, we have production servers that host both IIS &amp; SQL on the same machine, not ideal but no flexibility to change that. 

Basically a single machine is both a DB and an Application server, hosting multiple DBs and multiple instances of ASP.NET sites.

The last time I checked MS' best practice said ~75% RAM allocation to SQL, however this config doesn't leave much room for other processes to run.

Does any one know what Microsoft recommends for servers that host both SQL &amp; IIS together ?
When there's nothing else on the machine besides SQL you need to leave at least 2-4 Gigs of RAM for the OS.  When running a bunch of different IIS sites you'll need at least 4 Gigs for the OS and IIS.  As some of your machines have only 4 Gigs that's a bit of a problem.  Can you add some RAM to these servers to get them up to 16 or 24 Gigs?

I'm assuming x64 here?