Can anyone share their experiences (for example, this was great! This failed miserably!) with using the Hyper-V, ESXi, and XenServer virtualization platforms? Cost? Management? features? Handling load and backups and recovery?

And also minimum server requirements?

I thought Xen was a free virtualization platform for Linux. Is there a Xen and a separate XenServer platform?

Opinions and observations would be appreciated for a test rollout for our organization.

  • 2
    Each of these solutions has it's pros and cons. If you could mention your requirements / scale you may get a more valuable answer. Google will supply you with lots of 'comparisons' but by supplying a real situation folks can give you the specifics that go beyond the typical Google result. Jul 23, 2009 at 13:49
  • I've been googling and reading about them, what I mainly wanted was to hear a reaction from other admins that had tried using them. I.e., we can all read about how wonderful RAID is, but I had a hardware RAID 5 go bad when a drive died and wouldn't rebuild with a new one because another drive had one bad block on it that never triggered an alert on the controller...hoped to find similar anecdotes here that aren't found in the literature, so to speak. Jul 23, 2009 at 14:28
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    Thanks for the reply Bart. Where I was going is that if you are only talking about a handful of VM's on 1-2 physical hosts, any of the solutions will work for you. They begin to differentiate when the requirements move to advanced management functions, high availabitliy, seciruty, types of more extreme workloads, current administrators / environment preference (Windows vs linux really). Jul 23, 2009 at 15:21
  • I prefer being able to experiment with home network setups, which means that the more $$ the worse for me, but at our organization we're currently moving Windows XP/2000/2003 based systems (printer/file sharing mostly) and a Linux web server (bulletin board, internal use) to a system. The hardware has 16 gig RAM, 2 4-core processors, gigabit ethernet (dual gigabit but don't know if there's support for bonding them on a hypervisor). Our current vm server has four lightly-used systems on it with a few more scheduled to be migrated over (using EXSi). Jul 23, 2009 at 15:25
  • 1
    Don't forget RHEV (redhat.com/virtualization/rhev) or Ubuntu KVM with ganeti
    – ptman
    Jul 12, 2011 at 16:23

9 Answers 9


I recently took all three for a spin to run my home network, and the short answer is that it depends on your particular needs. Unless your needs are very specialized (database/Exchange/etc), modern hardware with virtualization support you will run the guests with negligible performance differences. Given that I'd suggest looking at features & price.

VMware: As you're probably aware VMware is the long-standing king of virtualization. It has the biggest list of compatible guest OSs, and has one significant unique feature - memory overcommit (you can allocate more virtual memory than there is physical memory). If your goal is to consolidate a bunch of small, underutilized servers VMware will likely give you more VMs/host than anything else. The caveat is that if you overcommit and the VMs need more resources performance tanks. ESX/ESXi also has the smallest list of compatible hardware. If you are looking at a white-box system, check here first. If you have compatible hardware it's fairly easy to install and use. The free version (ESXi) comes with hardly any features, which is fine if you're looking for a few standalone hosts, and the non-free versions are priced out of this world. On a personal note, I VMware leaves a nasty taste in my mouth - in my mind they are one of the many companies resist change & innovation when the very foundation of their business is challenged by the competition. Recently they asked a partner company to remove their product's support for the free version.

Microsoft: Hyper-V is a very intriguing option, even more with the R2 version. I tested Hyper-V Server, which is the free standalone product. I'm a Microsoft fan, and I really wanted to like Hyper-V, primarily because it can run on practically any hardware that has Windows drivers. If you are running in a domain environment and primarily use Windows, Hyper-V should be at the top of your list. When you have the option to buy/use SCVMM it appears to be an even better value. Unlike VMware, the free version comes with a good feature set and is even better in R2, where clustering & live migration are available! Hyper-V runs Windows guests very well, has a small, but growing, list of supported Linux guests, and even unenlightened Linux guests seem to run reasonably well. The story is different if you aren't in a domain environment as managing the standalone Hyper-V Server is a major pain. Despite all of the goods Microsoft delivered in a v1 product, the management was driving me crazy.

Citrix: The end result of my testing was to go with XenServer 5.5. It has IMHO the best set of features and capabilities of the three free offerings. Like VMware it is installed and managed like an appliance rather than an operating system (like Hyper-V). It also has a much larger list of compatible hardware (and I suspect the ability to add drivers if needed). It offers way more features than VMware's free offering, and if you were to upgrade the free version to the paid version would cost much, much less. Windows guests are well supported, but Linux guests are, well, not what you'd expect from a Linux-based virtualization platform. Its list of supported Linux guests is quite small compared to VMware and non-supported Linux guests don't seem to run well at all. Ubuntu is noticeably lacking from the list. Overall for home use I felt that it had the best bang for the buck.

  • I agree; XenServer 5.5 has the best set of features that are free out of the box. Overall a great summary on the product OEMs themselves too.
    – osij2is
    Jul 29, 2009 at 20:36
  • Can't understand the issues with non-domain joined Hyper-V... been using it for some time without any problems...
    – Dscoduc
    Oct 12, 2009 at 2:16
  • @Dscoduc - Just personal preference more than anything. Sure Hyper-V works without a domain, but if you ever wanted to take advantage of the higher-end features you get for free with Hyper-V Server (CSV, Live Migration, etc) you do need a domain. With XenServer you get those kind of high-end features without needing a domain and with the ease of an appliance. Oct 16, 2009 at 14:18
  • Love citrix XenServer. The XenCenter console is a great product. Makes everything easy to manage. Can't go wrong with XenServer. Xen is a free product and in some cases has some more features as Citrix bases their XenServer product on Xen and contributes quite alot to the Xen project, sometimes working in tandem. If you go with Xen there is an open source project that copied the Citrix XenCenter project. I would recommend it. openxenmanager.com
    – user75720
    Jun 2, 2011 at 21:10

I thought Xen was a free virtualization platform for Linux...is there a Xen and a separate XenServer platform?

Yes and confusion is common.

  • Xen - The HyperVisor that sits behind the scenes.
  • XenSource - The open source virtualisation project/solution now owned by Citrix.
  • XenServer - The closed source virtualisation product produced by Citrix.
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    It's worth adding that xen is not linux, nor is it a virtualisation platform for linux. It's just a hypervisor. There is a codebase to allow linux to be the dom0 admin/IO domain and this is the norm. But you can also have other OS as dom0 e.g. open solaris
    – goo
    Jul 29, 2009 at 19:45

Quite general what your asking however these are three very big products in the virtualization world, and all offer trail periods i'd advise on taking out testing them on some spare hardware. I can give you my experiences of what I know in the three but would be nice to hear from others too

VMware vSphere 4 First off it's the market leader, and has great dominence over the lot. I costs more but depends what your looking for. ESX (ESXi or ESX HD install) as a single managed host is free. You pay for clustering and management features, HA, DRS+DPM, FT This gives a good comparison vSphere Compare

Other advantages i've found is the CLI and API options. it's endless the amount of automation and support for a large user community. Lots of plug-in's to chose from too.

Citrix XenServer This I'd second as Citrix are great for desktop delivery, and I guess XenServer will be a power product for there suite of stuff. yet to test it. just need to find time but so far it looks neat. It's based on the free Xen.org so it will have a growing user community behind it. This is also on my evaluation list, however ours own IT use it for production VM's, will have to get there views.

MS Hyper-V As MS know they have to enter this industry it eventually mature and match the feature of it's competitors. I'\ve yet to test this hypervizor out.

As regards testing. Make sure you have large servers, 2xQuad CPU's 8GB+ RAM, iSCSI or FC SAN makes a huge difference to test on decent hardware.

Hope that helps ;)

  • 2
    So basically you have only tested the VMware product?
    – Dscoduc
    Oct 12, 2009 at 2:25

Cost: XEN and Hyper-V are likely going to be cheaper products in the short run.

Storage compatibility: You really want a decent SAN to drive your storage.

Tools: VMware is king here. VirtualCenter, Lab Manager, LifeCycle Manager, Backup Assistants. Citrix/Xen is only just starting to build tools of this functionality (although the VMware tools CAN be horribly buggy at times).


Everyone's comments so far are on par with my own experiences. ESXi is a great (free) intro into the VMWare platform. I'd also recommend XenServer 5.5 and XenCenter, both free from Citrix. I currently use Citrix XenServer 5.5 at home and it runs extremely well and XenCenter makes administration so easy. I've been very impressed with the product as a direct competitor to VMWare's product line.

In terms of cost, VMWare is the most expensive but the most mature and stable platform. I'd say Citrix is next in pricing, and MS last as they're practically giving away (~$30?) Hyper-V.

And as usual features come with a price tag. More $$$, more features so I'd say for you maybe the better tactic is to investigate what you think you need first. Then list out features you want. Then work from there, and investigate solutions. Anything extra should be noted.

Opinions and observations would be appreciated for a test rollout for our organization.

So it sounds like your organization is trying to test out the waters. If testing the waters is all you can do, start with price. ESXi 4.0 and/or Citrix XenServer 5.5. If you're strictly running a Microsoft platform, I would recommend Hyper-V as an alternative.

  • With Hyper-V don't you have to license Server 2008? Jul 23, 2009 at 15:27
  • I don't work with Hyper-V on a regular basis so I can't answer your question accurately. Microsoft's website may be a better source than me for licensing: microsoft.com/windowsserver2008/en/us/hyperv-faq.aspx
    – osij2is
    Jul 23, 2009 at 15:31
  • Hyper-V Server 2008 is free - Details here microsoft.com/downloads/… . You need to accept the license terms, it is closed but you don't have to pay for stand alone Hyper-V.
    – Helvick
    Jul 23, 2009 at 17:44
  • Guess they're giving it away for free now. If you can't beat 'em, give it away!
    – osij2is
    Jul 23, 2009 at 18:18
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    If your guest OSes are non-Windows, it's complete free. If you use Windows, then you need to license the guest operating systems. Or, if you license Windows Standard, you get to install it as the host and guest with the single license, or Enterprise edition allows 4 guests, and DataCenter edition allows unlimited guests. Not everyone realizes it, but the same licensing applies to VMWare and XenServer too. For example, 1 license of Enterprise allows up to 4 guests on the same host. Sep 7, 2009 at 0:07

I don't have much experience with Hyper-V, but from what I have seen and heard, it's the classical MS market-entry: it's just good enough, but don't expect anything fancy (like proper live migration, without any strings attached). My personal opinion: if you value you machines' uptime, don't do this. The technology just isn't mature enough yet.

VMware is market leader for a reason. It's easy to manage, even if you do not have much virtualization experience. It's stable, fast, mature, scalable and expensive. Probably the best product you can get.

Xen is built into a lot of free Linux distributions, but in such a setup, it is a little more complicated than VMware to manage. A little, not much, especially if your shop is not too big. All major distros have Xen and / or KVM these days: CentOS, Debian, Ubuntu, Fedora. If you want paid support, RHEL and SLES provide it. Xen has a huge userbase, just like VMware and yes, you can get it for free, though your evident lack of experience urges me to suggest you buy proper support for it. I would recon Xen's price / quality ratio is a little better than VMware's.

  • Hyper-V R2 (part of Server 2008 R2) has just gone RTM will a lot of enhancements, including live migration.
    – Richard
    Jul 23, 2009 at 14:52
  • So purchasing 2 licenses of Server 2008 will allow live migration of VM's between two machines? Is there a catch? Jul 23, 2009 at 15:55
  • You need to purchase either Enterprise of Datacenter Edition of 2008 R2 to support it - the basic requirement is that you set up a failover cluster first. This will require shared storage too.
    – Helvick
    Jul 23, 2009 at 17:50
  • "JUST gone RTM". Vmware has been doing live migration since Y2K. I'll stick with the proven product, thank you very much.
    – Chris K
    Jul 23, 2009 at 19:21
  • @Rcihard, tell me, is that the real thing, without having to use a LUN per VM or without having to failover all VM's on a LUN? Because that is / has been a bit of a problem, isn't it? Afaik, Hyper-V can do some sort of Live Migration, but it is a bit of a hack, since machines are shortly suspended during migration. And then still, because of the usage of NTFS, you either have to place a VM on a LUN by itself, or migrate all VM's on a LUN. NTFS is not a cluster file system, after all. Or at least, so I heard :P
    – wzzrd
    Jul 24, 2009 at 7:21

Keep in mind that VMWare offers ESX and ESXi, which are basically the same but not exactly the same. As mentioned above ESXi can be utilized as free software with most all of the features you would need to try out the software and even use it in a limited production capacity, however if you want to have support from VM (which I have found to be a very knowledgeable group) you will need to pay for the license. Some of the key differences between ESX and ESXi include different command line toolsets, as well as general architecture differences meaning that for example console access on the box is radically different. In general, if you decide to try ESX I would definitely try the free version of ESXi first but I would not necessariyl count on using that in production.

  • 2
    Why not use ESXi in production? VMWare is pushing ESXi as their primary hypervisor and I have seen ESX listed as "supported for legacy customers" in more than one of their documents.
    – MDMarra
    Jul 23, 2009 at 17:38
  • Fully agree - there is no reason not to use ESXi in production but I would still advice that it be fully licensed in order to avail of support. And as you say VMware have said that they are moving to a Hypervisor based on ESXi rather than ESX in future.
    – Helvick
    Jul 23, 2009 at 17:52

Anyone considering anything other than Hyper-V needs to understand the following KB article: http://support.microsoft.com/kb/897615. Large corporations with Premier support accounts will not be as effected as smaller companies. Support needs to be the first consideration of a hypervisor.

Beyond that, VMWare is the king of features. Analysts and pencil pushers who never use these products use VMWares features as a list of "must-haves" as if VMWare is lining their pockets with gold.

Hyper-V has most everything that is needed as a baseline, but lacks the ability to bond NIC's on the hypervisor. IMO, it is a poor decision to depend on 3rd party "teaming". HyperV has the best UI when used with SCVMM. SCVMM is lacking integration into the other System Center products, so to get the full solution, you really need to license the SystemCenter Suite. SCVMM can be used to manage VMWare environments as well, but no Xen-love at this time.

XenServer is the IO king. If you run XenApp, the only virtualization to consider is XenServer. XenCenter Mgmt console is clunky at best.


Questions like this always end up being a religious decision. For the most part all three of these platforms have their strengths and weaknesses. Looking over everyone else's answers it's pretty clear that each person has their choice of platform regardless of the facts...

To correct a previous incorrect statement...

Hyper-V has most everything that is needed as a baseline, but lacks the ability to bond NIC's on the hypervisor.

Hyper-V synthetic interfaces are bound to the hypervisor, and the Hyper-V product has most everything (if not all) you will find on other platforms.

Lastly, I would suspect that all vendors are going to end up offering the base Hypervisor for free and the profit will come from management and add-ons.

Enterprise virtualization decisions really need to be made with product comparisons and considerations of the product road-map.

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