James O'Neill's Blog

October 20, 2008

Hyper-v Server , what is it exactly ?

Filed under: Virtualization,Windows Server,Windows Server 2008 — jamesone111 @ 12:07 pm

I’ve got multiple blog posts on the go in Windows Live Writer at the moment, one talking of the relative dearth of posts recently. Last week the folks at VMware put up another post about Hyper-V server and in it actually found something nice to say about me (even if they mis-spelled my name. double-L guys, like the wet-suit and surf gear maker).  I’ve got to say something nice about them and getting products certified, but that’s another post.

Before this becomes a love-in, lets get back to Hyper-V Server … what is it then ? From the point it was first mooted, we’ve been saying that the easiest way to picture Hyper-V server is as Windows Server 2008 Standard Edition, Core Installation, with only the Hyper-V role available. That is an over simplification but as a first approximation it will do. In that post VMware’s Tim Stephan post says “I am actually thinking that, at the time of Hyper-V server’s announcement, Microsoft itself didn’t know what the Hyper-V Server 2008 architecture would look like…”. Not so: the idea of Server Core (standard) with all the bits what weren’t needed removed has been pretty constant even if the odd wrinkle needed ironing out between announcing and shipping.

The VMware post says “Hyper-V Server is supposedly Microsoft’s ‘thin’ hypervisor that doesn’t require Windows Server OS in the parent partition – as reported by Microsoft here.” 

“Here” is Post of Patrick’s where doesn’t say those things. He does say:

  • Hyper-V Server 2008 was built using the Windows hypervisor and other components, including base kernel and driver technologies. Microsoft Hyper-V Server 2008 shares kernel components with Windows Server 2008.
  • Microsoft Hyper-V Server 2008 contains a sub-set of components that make up Server Core deployment option of Windows Server 2008, and has a similar interface and look and feel. But as you know, Server Core has roles like DNS, DHCP, file. Hyper-V Server 2008 is just virtualization.

  • Because Hyper-V Server 2008 shares kernel components with Windows Server 2008, we don’t expect special hardware drivers to be required to run Microsoft Hyper-V Server

So, strictly speaking, it isn’t the Windows Server OS in the parent partition, but everything which IS in the parent is from Windows. If it wasn’t, you wouldn’t be able to manage Hyper-v Server like Windows Hyper-V, you wouldn’t be able to use the same drivers use the same patch process and so on.  And since I mention patching, do you need to download the same patches as for Windows Server 2008, Standard, core with only the hyper-V role ? Yes. The guys at VMware found that out. Incidentally, the client Windows Update uses some parts of internet Explorer to get updates over HTTP, and to find and connect through proxy servers. It might feel wrong to be applying an IE patch to Hyper-v server or Server core, but that’s the reason and not every IE patch will be needed.  Running a Microsoft OS in VMs, and as the host everything get’s patched together. Customers can judge VMware’s Patch record and Server 2008’s for themselves; I’m happy to be on the Microsoft side in that one.

One might quibble with their sensationalist tone “Microsoft OS based on Windows shock” … what did they expect, VHD’s stored on a whole new file system ? Windows PE as the management partition ? A whole new driver model ? They come to the conclusion that the easiest way to picture Hyper-V server is as Windows Server 2008 Standard Edition, Core Installation, with only the Hyper-V role available, as if we hadn’t been saying since before it was announced.

So does the rest of the Tim’s peice introduce any new FUD or distortions. Not really. Their comparison chart is the same old spin

  • Having laboured the point that Hyper-v Server is based on Windows, they claim it isn’t production proven, and is hard to move VMs to other products in the Microsoft family. I don’t think the facts justify those opinions (no surprise in that) But what constitutes an easy upgrade ? What constitutes production proven … do you need more proof or less than the next customer ? I don’t trust things which present opinions as facts (people point out when I do it, and I when I’m not clear I get annoyed with myself). 
  • Memory support in Hyper-V Server is capped at 32GB like Windows Server standard. There’s no clustering support (like Windows Server Standard).
  • VMware takes up less disk space than its competitors (though with disk space these days costing less than £0.10 per GB I’m never sure why they bring that up. VMware has a bigger memory foot print (see this post from Roger Klorese ) – depending on configuration Hyper-V uses about 200MB less. So no-one should be surprised that they gloss over that one.
  • I’m suspicious of their Supported guest OSes figure. Our 11 is “OSes which you can call Microsoft support and get a fix for if they don’t behave properly on Hyper-V”. We don’t support NT4 on anything any more. There’s actually a check box in Hyper-V to make it run better, but running well is not the same in Microsoft product-support parlance as supported. My understanding is that their 30 is “OSes which are known to work”, so that would include NT4. I’m not going to argue for any particular definition of “supported” but you can’t make a valid comparison unless the definitions are the same.

This post originally appeared on my technet blog.


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