VMware decided to make their ESXi product free as of July 28th!

This is gonna make Hyper-V adoption slow down to a crawl for sure.

The overhead is smaller: it uses only 32MB of disk space total, it can run more simultaneous VMs on the same hardware (memory overcommit -- 40 VMs with 512MB each running in only 4GB of RAM anyone?), and seemingly it has better I/O performance too (MS was caught using SSDs to make their product's speed look decent). And even before it was free, it was a whole lot cheaper than Win 2008:

-ESXi was $495, and that was your total expense (now $0)
-Win 2008 standard with Hyper-V is $999, plus an extra $140/every 5 users for extra CALs (only 5 included) e.g. $700 more if you need 25 extra CALs

And ESXi has more features too, like live migration, and being able to add more RAM to a server without even having to reboot it.

With this, I can't think of any reason to use Hyper-V anymore.

Wow. That'll be something interesting to look at in the near future. I've been working on setting up some virtual servers at home for various purposes, but which product to use is still in question.

Nice one.

I'm not a fan of Vmware and prefer Virtual Box for my emulation needs but this is a very cold shower on the MS machine..

No excuse to avoid ESX now.

Well, do some research into the macrokernel+vendor provides hypervisor drivers versus microkernel+root partition+synthetic drivers architecture (ESX vs Hyper-V) before assuming VMWare's offering is better than Microsoft's.

There are a lot of drawbacks with a macrokernel hypervisor like ESX uses, and there are some pluses as well. Especially if you're going to run a lot of non-Microsoft VMs and want integration components, ESX is going to be a better choice due to better non-Microsoft OS support. If you're going to run a lot of Microsoft VMs, however, hyper-v is likely going to be faster (and if you run Vista SP1 or Server 2008 VMs that are enlightened for the hypervisor in kernel, they'll be much faster on hyper-v).

There can also be some security issues with a macrokernel you won't run into with a microkernel hypervisor, and you can also find it more common for a misbehaving VM driver in a macrokernel hypervisor to affect the rest of the VMs than would happen in a microkernel hypervisor (because the VM's drivers don't go directly into the hypervisor, and thus the root has more control).

The macrokernel is going to be a tad faster than a microkernel hypervisor, because you don't have accesses through the root partition drivers thus increasing speed. AMD-V and Intel-VT significantly reduce this hit at this point, but it's still there and ESX still provides a bit better I/O to a virtual disk. Once the next versions ship with Nehalem and the next Opterons, this will shrink, but an I/O intensive VM should be using a passthrough disk anyway .

It's pluses and minuses on both sides, you have to decide which pluses you want, and which minuses you can live with. I've used both ESX and Hyper-V extensively, and the only reason I would choose ESX at this point would be if I was virtualizing a Linux or another Unix-based OS.

news source: http://www.informationweek.com/news/softwa...cleID=209400823
product page: http://www.vmware.com/products/vi/esx/esx3i.html

Wow this is quite a move, I think I hear some chairs being thrown. I am not really surprised by this news, I think its a smart decision by VMware, but I wonder how long this will last? I hope this makes Microsoft develop Hyper-V faster too.

As Cluberti mentions although both are level one hypervisors there are still fundamental differences between them that have pros/cons in different situations. What's interesting is VMware claims ESX uses a micro "vmkernel", but that it wraps around the Linux kernel (not micro). I also wonder what the difference is between 'Enlightened I/O' and 'VMI'?

I hope we see some independent and accurate benchmarks for these products soon.

[EDIT] 3000 posts!

Correct, VMWare's hypervisor is a MACROkernel, but now they're trying to pass it off as NOT being a macrokernel (well, it's easier than a rewrite to use confusing terminology to fool buyers/customers/users, but it doesn't change anything). I guess marketing sells (or in this case, gives?).

As to Enlightened I/O, OSes that have a kernel that understand a hypervisor and are written to run in a child partition on top of a hypervisor actually will be able to run faster because they "understand" how to run virtualized, and bypass a lot of overhead by talking to the VMBus and the hypervisor directly (this is NOT the same as installing integration components - those just make the drivers in the VM more efficient, they do NOT "enlighten" the VM - the VM's kernel must be written to "understand" the VMBus and how to speak to it directly).

VMI is "paravirtualization", meaning you have one "root" kernel (in this case, Linux) and "child" kernels running as a "guest" of the root OS (hey, sounds like emulating a microkernel!). The benefits to this are that there is only one real OS doing the "kernel" work, and it is controlling all of the guest partitions inside it running the guest OSes. It's not actually a real "hypervisor" approach, but it does make child VMs faster than type-2 virtualization. VMWare's take on this, if I understand it correctly from their spec, is to install the root Linux partition into the hypervisor, and run the guest partitions off of that root hypervisor VMI (again, sounds a LOT like microkernel design).

hrrg, it works perfectly... thanka again for the great tip with esxi

Those who question the choice between Hyper-V and the failing VMware ESXi have obviously not used Windows 2008.

Or perhaps they want to virtualize pre-win 2008 OS'es (win 2003 is still a VERY capable server OS), other versions of Windows, Linux, BSD, Solaris and others, without needing to spend $1000+ on a Win2008 license for every box. Is Hyper-V really $1000 better? I think not.

And yes, Win 2008 uses enlightened I/O, but then again even with that it's I/O is slower than VMware anyways (they had to resort to cheating, using SSDs to make their IOPS benchmarks look even close to VMware's)

You can easily virtualize 2000, XP, 2003, and 2008/Vista easily - it's just that you need 2008 or Vista SP1, or a Linux with a Xen kernel to get enlightenment in the OS. As to hyper-v licensing, if you purchase datacenter (and yes, it's costly, but hear it out) you get unlimited virtual licenses. Unlimited. And you can downgrade those licenses at will to run lesser OSes, also unlimited licenses. Does this help the small business? Probably not, but if you're buying hyper-v to consolidate servers, you probably want to get 10:1 or more per server consilidation, and once you start purchasing 3, 4, more servers to do consolidation, it actually (price-wise) makes sense to purchase datacenter for those servers and use the unlimited licenses (Enterprise gives you 4 freebies, not to be totally out in the cold).

And long term, using a microkernel + synthetic drivers will actually provide better overall performance vs VMWare's macrokernel/paravirtualization model. Also, this being a v1 product, it's not exactly feature-complete compared to ESX, and I can easily and readily admit that v2 of hyper-v will compete far better. However, hyper-v has no features I absolutely must have missing that VMWare provides, and I can wait for live migration support until V2. Hyper-v isn't exactly slow on I/O, and the only load I still won't put on a hyper-v box is SQL (and that'll change with SQL 2008, hopefully, but I've not tried/tested it yet).

By the way, $600 for a Windows Server 2008 Standard license with Hyper-V is not exactly breaking the bank. We're consolidating 9 super micro servers into 2 Dell PowerEdges running Server 2008. We already tried the VMware approach and it was a total mess compared to this.