I know that it has been officially unsupported forever and yet I have seen or heard about many small business installations of a single host running AD DS and Exchange simultaneously. For a resource-strapped small business the savings are compelling.
So assuming that we know somehow that usage requirements will never grow beyond 25 users, say 10 simultaneously,
- How "bad" is it really these days to run both Exchange and AD DS on the same machine (sans virtualization of any kind)?
- What specifically is bad about it? (Name the top 1 or 2 reasons that come to mind besides "Microsoft says so")
- What can be done to mitigate the "bad"ness, if anything?
You can assume that the business in question either:
- has a single physical on-site server with a reasonable commercial ISP or
- has a pool of virtual resources that is already tapped out and they do not want to spend more.
The situation I have in mind is the second, with just one VM that could possibly be a candidate for adding Exchange because it is the only Windows VM and has enough excess memory to make it happen.
In any case, the reasoning may not be all that, well, reasonable, but let's say those are the constraints you have to work with.