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This is a variation on, except with virtualization.

A vendor is suggesting to install Exchange, Active Directory and two domain controllers on a single high powered server, running Microsoft Server 2008 with Hyper-V, using several virtual OS to isolate the services.

Is it wise?

Is it supported?

Should we consider VMWare instead of Hyper-V?


share|improve this question
If you need more than a few (~3?) virtual Windows servers, note that Windows Server Enterprise should be licensed for an unlimited amount of virtual instances which depending on local pricing and how many guests you need could mean some cost savings if considered. – Oskar Duveborn Sep 17 '09 at 19:27
@Oskar I thought Enterprise came with only 4 guests Windows Server licences – Mathieu Longtin Sep 17 '09 at 20:41
BTW, Thanks for all the great answers. – Mathieu Longtin Sep 18 '09 at 3:28
up vote 4 down vote accepted

A vendor is suggesting to install Exchange, Active Directory and two domain controllers on a single high powered server, running Microsoft Server 2008 with Hyper-V, using several virtual OS to isolate the services.

As long as each server is in it's own VM guest, everything should run fine. I'd recommend having another server for failover/load balancing/whatever.

Is it wise?

Yes in terms of budget, but beyond that, it's not too bright. Obviously money is always an issue so if management or the powers that be can live with a little risk, than this should be seen as a short-term solution. And by short I mean no longer than 12-24 months. After that you're gambling. If the timeline is really fuzzy, buy/obtain high quality server parts to reduce the probability of failure.

When budget increases or when the opportunity arises, another server (at a minimum) should be considered for virtual live migrations and such to avoid the dreaded single point of failure.

Is it supported?

Yes, there's no evidence or vendor really saying this can't be done. I've done this with 4 Windows 2003 Standard Servers running AD, Exchange, etc. etc. on one VM host. As long as the hardware is within the specifications, just about anything is possible.

Should we consider VMWare instead of Hyper-V?

If all of the machines are Microsoft servers, I don't see any harm in running Hyper-V. All that should be taken into consideration is features and really, it's hard to argue against Hyper-V these days.

I would ask you where do you see things going in the future and base decisions off of that. If money looks to always be an issue, I'd personally stick with Hyper-V or consider XenServer. I'll admit my bias towards XenServer 5.5 as a great free introduction into virtualization with great features and management tools. ESXi and Hyper-V both have their merits as well, but it's hard for me to assume what's better for you as your situation hasn't fully been explained.

On a side note, most virtualization projects really come down to money. I wouldn't look at this issue as so much from the technical perspective as virtualization vendor products these days are very mature, stable and reliable. So really for most businesses it's about money which is obviously always a concern but in this economy, the finances become the biggest obstacle. So do some "if-then-else" future scenarios and see if the money will be there or not and look to the vendors and see what features they offer for free, and what features are only available for money. I'm willing to bet this will be your biggest factor in decision making today.

Edit: I should've been more clear about XenServer; I'm specifically referring to the Citrix version of XenServer 5.5.

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We do this, and we've never had a problem. You should never combine these roles in the one logical OS, but breaking up the one server should be fine, especially if they're not in high demand roles.

That said, it's a bit strange to have more than one DC on the same physical host. The point of multiple DCs are:

  • Redunancy
  • Load Balancing
  • Point of Presence

Putting them all on the same host negates all this. You don't get redundancy (if the host fails, you loose them all). Load balacing is moot (you're taking resources from the other DCs, so where's the point), and because they're all in the same physical location you don't get a local POP for outside offices either.

Apart from that though, go for it. VMWare is nice, especially with vSphere, but for one host it's not worth it (especially if you look at the price of VMWare)

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Best practices is to have at least 1 DC physical, and further DCs can be virtual (and on any host you like) - so long as you have the physical to fall back on if the host dies. – Izzy Sep 16 '09 at 21:34
If you are running 1 server, use ESXi - the price is free and you can convert it to a vSphere capapble license as your grow. – Zypher Sep 16 '09 at 21:45
I KNEW someone would say that. The hypervisor might be free, but take a look at the rest of the prices. VMWare is NOT free if you want to use it properly, or have backups, or any sort of redundancy. – Mark Henderson Sep 16 '09 at 21:47
Well, Windows Server 2008 isn't exactly free, too. And with ESXi you get full ESX virtualization capabilities; you won't have centralized management and clustering, but if you have a single host you definitely aren't going to manage it centrally and/or cluster it. – Massimo Sep 17 '09 at 15:51
Xenserver folks. Xenserver. – Izzy Sep 19 '09 at 7:10

I'm a bit skeptical of any vendor recommending you install a 2nd DC VM on the same physical box. As Farseeker pointed out, this defeats the purpose. I might get a 2nd opinion from someone who understands why you should have 2 DCs in the first place.

VMWare vs. Hyper-V - once you cut away all the marketing, MS is doing its best to keep pace and add the same functionality for similar prices from VMWare offerings. ESXi is free, Hyper-V is also free. Once you want features beyond creating & running those VMs, you'll be paying either way. I run Hyper-V, and it seems that it's a bit behind VMWare in a few areas, still. That said, it's doing what I need very reliably.

There's no real reason NOT to do this, save that you have all your eggs in one basket. If your backup plan is sound and you're aware/comfortable with everything being down for as long as it may take to replace a motherboard (or keeping a spare of everything on hand), it's do-able.

My own approach was to make sure my plan included two moderately-powered physical servers to host our VMs. Each runs its load of virtual servers comfortably, and should a failure occur on one, I have the option of moving the VMs (or restoring from backup) to the other. It'll run slowly, but the downtime would be minimal.

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Maybe you meant "two moderately-powered physical servers"? :-) – Massimo Sep 17 '09 at 16:09
Doh! Thanks - dis-ambiguized. – Kara Marfia Sep 18 '09 at 11:11

There's no software reasons not to do this that I'm aware of, but I'd be wary of installing both domain controllers on the same physical iron. If something disastrous occurs with the physical machine you lose your whole AD.

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If you have only a single physical server available and hardware resources are not scarce, it's a lot better to use it as a virtual machine host and create many VMs to properly separate your roles; Exchange doesn't really love to be on a DC (especially if it's your only one), and going virtual will allow you to create other VMs in order to do things that would really fight each other on a single server. If f.e. you will need a database server, a web server, a firewall, an anti-virus server and a WSUS server, all of them would have a lot of troubles coexisting on the same server, while they would happily run on separate VMs if the host has enough resources for them.

Personally, I'd recommend VMWare ESXi; for a single host it's exactly the same as ESX, but it's free; it doesn't give you clustering or centralized management, but if you have a single host to run, this doesn't matter a lot. I'd recommend it over Hyper-V for three main reasons:

  • It's a lot more mature; VMWare has been doing virtualization for years, it does only that and does it very well.
  • It has much less overhead than Hyper-V, which needs a full Windows Server 2008 running on the host system.
  • It's free.

About the "two domain controllers" issues: if you have resources for the VMs, having two DCs is always better than one. Sure, you will still have a single point of failure (the host), but with two DCs you will be able to withstand a software failure on of one of them, which can always happen, and you will also be able to reboot each of them (patch management anyone?) without taking the whole network down.

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Hyper-V does not need full Windows Server 2008, I'm not sure where this idea came from. Hyper-V is available as a stand-alone product. – ThatGraemeGuy Sep 17 '09 at 18:55
The OP stated it clearly: "a single high powered server, running Microsoft Server 2008 with Hyper-V". – Massimo Sep 17 '09 at 19:24
Yeah, definitely a common misconception, but seeing how Microsoft isn't exactly marketing the stand-alone edition much it's not surprising. Also, that stand-alone download clearly states "requires Windows Server 2008" on the download page which is also a tad misleading (though technically correct but it's included in the free download of course). – Oskar Duveborn Sep 17 '09 at 19:32
The OP's misconcentions aside, I was specifically referring to this part of your answer: "... less overhead than Hyper-V, which needs a full Windows Server 2008 running... " – ThatGraemeGuy Sep 17 '09 at 21:10
If you need something fancy as failover clustering, you actually need a full Windows Server 2008 installation; but I agree, running Hyper-V Server has only a minimal overhead, comparable to that of ESX. – Massimo Sep 17 '09 at 22:29

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