cheers for the insight steve.

Its those things on the C drive that a SQL install places on the C no matter where you actually ask for the install to go to. i.e the things that go into program files\microsoft SQL server, such as binaries for the tools I believe go there, and of course information held in the registry.

Our system databases are placed on the SAN so have the potential to be replicated by SRDF. If we do replicate them I was wondering how others who do that handle SQL upgrades to the SRDF pair to keep the binaries on the C in line with the system databases.