Reading this thread is somewhat amusing. I think people have been reading the best practices docs for so long they've stopped thinking about why the docs say what they do.
Adding a server to put the DC on separate hardware from Exchange does not increase availability. In fact, it *decreases* the availability of Exchange. With the DC on a separate server, if you lose the DC, you also loose Exchange. So now you've got twice as many failure points as before. I've seen this called the "airplane rule": A twin-engine airplane has twice as many engine problems as a single-engine plane. Sometimes you really want that second engine (like on a plane), but don't loose sight of the forest for the trees. Having a separate DC increases availability if you have *multiple* separate DCs. That's a real gain, since if you loose either one, everything keeps running happily on the other. (Modulo FSMO roles and GC.) Distributing services is always nice. Ideally, we'd put DNS, DHCP, WINS, Exchange, DC, file, print, and databases each on their own server, and each application would have its own server, and we'd have cold spares for everything, too. But putting them together doesn't cause instability in the space-time continuum; it just means more things go down with that one box. In a very small company, it's not uncommon to find everything tied together *anyway*. See the DC example above. Of course, software conflicts and the like do exist. In my experience, Microsoft PSS is a bit schizophrenic about the whole DC+Exchange thing. They say you shouldn't do it, but then when you ask, "What about SBS?", they say, "Well, okay, yah, there's really nothing wrong with it, we just don't recommend it.". They seem to want it both ways. That said, I've run single-server environments for years, and I've never really have much of an issue. But I'm careful about my IT management practices, and make nightly backups. Performance analysts will cringe at this, but a typical single-server environment is handling maybe 20 to 80 users. With today's hardware, you can be in the mud in terms of theoretical efficiency and still handle a workload that small. Another thing to consider: For most very small companies I've dealt with, the plan for large-scale disasters (e.g., building burns down) is called "chapter 7 bankruptcy liquidation". Things of that scale are simply more of a hit than they can absorb. So there's no point in spending money on that scenario, at that stage. Just make sure you re-evaluate that decision as the company grows! -- Ben ~ Upgrade to Next Generation Antispam/Antivirus with Ninja! ~ ~ <http://www.sunbelt-software.com/SunbeltMessagingNinja.cfm> ~
