A couple of months ago we ran a webcast with Intel Fellow, Rich Uhlig, VMware Chief Platform Architect, Rich Brunner and myself. The goal was to talk about the past, present and future of virtualization. In preparation for the webcast we solicited questions from all of you, unfortunately we only had an hour during the webcast to address them. Rich Uhlig from Intel, Rich Brunner from VMware and our own Johan de Gelas all agreed to answer some of your questions in a 6 part series we're calling Ask the Experts. Each week we'll showcase three questions you guys asked about virtualization and provide answers from our panel of three experts. These responses haven't been edited and come straight from the experts.

If you'd like to see your question answered here leave it in the comments. While we can't guarantee we'll get to everything, we'll try to pick a few from the comments to answer as the weeks go on.

Question #1 by Andrew D.

How would you compare the product offering of VMWare to those of its key competitors, whit kind of performance hit can I expect running Windows from within a virtualized environment, are there any advantages/disadvantages for leveraging an Intel platform as opposed to an AMD one for a VMWare solution?

Answer #1 by Johan de Gelas, AnandTech Senior IT Editor

The performance hit depends of course on your application and your hardware. I am going to assume your server is a recent one, with support for hardware accelerated pages and hardware virtualization. You can get an idea of the performance hit by looking at perfmon and the taskmanager of Windows. In the performance tab of the task manager you can enable "show kernel times". The more time your application spends in the kernel, the higher performance hit. The performance hit also depends on the amount of I/O that you have going on.

If your app spends a lot of time in the kernel and has high amounts of I/O going on, the performance hit may be high (15-30%). But that does mean your application will have to suffer this performance hit. If you spend more time on optimizing (database buffering, jumbo frames) and if you use paravirtualized drivers (VMXnet, PVSCSI) the performance will get a lot smaller (5-10%). In short, performance hit can be high if you just throw your native application in a VM, but modern hypervisors are able to keep the performance hit very small if you make the right choices and you take some time to tune the app and the VM.

If your application is not I/O intensive, but mostly CPU intensive, the performance hit can be unnoticeable (1-2%).

AMD versus Intel: we have numerous articles on that on Anandtech. There are two areas where Intel has an objective advantage. The first one is licensing. The twelve-core AMD Opteron 6100 and six-core Xeon 5600 perform more or less the same. However if you like to buy VMware vSphere essentials (which is an interesting option if you can run your services on 3 servers) you get a license for 3 servers, 2 CPUs per servers and 6 cores per CPU. You have buy additional licences if you have more cores per CPU.

If your IT strategy involves buying servers with the best RAS capabilities out there, Intel has also an advantage. Servers based on the Xeon 7500 series have the best RAS features available in the x86 space and can also address the most memory. These servers need more power than typical x86 servers, but you can consolidate more VMs on them.

For all other cases, and that is probably 80-90% of the market, only one suggestion: read our comparisons in the IT section of Anandtech :-). The situation can quickly change.

Question #2 by Colin R.

How is the performance of virtualization of high throughput devices like networking and storage developing?

Answer #2 by Rich Uhlig, Intel Fellow

One trend is that new standards are being developed to make I/O devices more “virtualization friendly”. For example, the PCI-SIG has developed a specification for PCI-Express devices to make their resources more easily shareable among VMs. The specification – called “Single Root I/O Virtualization” (or SR-IOV for short) – defines a way for devices to expose multiple “virtual functions” (VFs) that can be independently and directly assigned to guest OSes running within VMs, and remove some of the overheads of virtualization in the process. As an example, Intel supports SR-IOV in our recent network adaptors. A big challenge with direct assignment of I/O devices is that it can complicate other important virtualization capabilities like VM migration, since exposing a physical I/O resource directly to a guest OS can make it harder to detach from the resource when moving VM state to another physical platform. We’ve been working with VMM vendors to tackle these issues so that we can get the performance benefits of direct I/O assignment through SR-IOV, while preserving the ability to do VM migration.

Question #3 by Bill L.

Are the days of bare metal OS installs numbered? If so, when should we expect to see ALL NEW servers ship with a hypervisor? Will hypervisors have virtual switches in them in the future or will network and storage traffic bypass the hypervisor all together using technologies such as SR-IOV, MR-IOV, VMDirectPath, etc.?

Answer #3 by Rich Brunner, VMware Chief Platform Architect

I do expect that at some point, bare metal hypervisor installs will reach a plateau in the enterprise and service provider environments, but I do not expect that embedded hypervisors will be the only alternative. There has been some industry buzz about PXE boot of hypervisors (this is much more than PXE boot of an installer) and a move toward a truly stateless model. I expect to see more of this; stay tuned. SMB may still want a turn-key solution which either has an installed hypervisor from the Server Manufacturer or an embedded hypervisor.

I do not expect that the network and storage control traffic will ever "bypass" the hypervisor; the hypervisor will always be involved in ensuring QoS, ACLs, and routing for this traffic. Even for SR-IOV, there is a fair amount of control required by the hypervisor to make this work. I can see that the actual data traffic can bypass the hypervisor to reduce CPU overhead provided that the hypervisor has sufficient audit control of this data. VMware and others are working to ensure that in the future for SR-IOV devices.

MR-IOV can be transparent to the hypervisor on a single system instance, but the load balancing is a perfect target for control by a centralized management agent across the multiple system images that share the resource (e.g. blades in a chassis share a high-performance NIC which is load-balanced by the management agent across the blades ).

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  • spddemon - Friday, July 23, 2010 - link

    you could buy thin clients and run citrix!! lol
  • marraco - Friday, July 23, 2010 - link

    Thin clients are more expensive than a monitor (the cost of USB keyboard and mouse is almost null). And today many processors on CPU are completely wasted.
  • shamans33 - Thursday, July 22, 2010 - link

    What's the best places (books, internet sites, etc) to learn more about virtualization?

    I'd like to know more about what's being offered out there (especially for hobbyists) and some stories about useful applications of virtualization. How is virtualization useful at home or for small businesses?
  • spddemon - Friday, July 23, 2010 - link

    Getting started is bit more of a challenge than it was 3-5 years ago.. Google is definitely your friend.

    There are quite a few books out there on virtualization for beginners. My suggest is to start playing with virtualization software and expand your knowledge base and go from there. VMware offers free evals of some of their products, but some of their products have stiff hardware requirements.. But, you can go and download VMware server and install it on windows or linux and start working with it. when you encounter a problem, google it. learn from it...

    There are a lot of different vendors offering virtualization packages.
  • Peroxyde - Thursday, July 22, 2010 - link

    Q1. What is the current (and near future) status of the use of Nested Paging and Virtual I/O to improve virtualization performance? Are these hardware extensions really useful or just hype?

    Q2. Technically, is there still any head room for improvement in virtualization technology? If yes, is it in the hardware or in the design of the Hypervisor? What would be roughly the scale of improvement? 10%, 100% or 1000% ?

    Q3. Is it possible to virtualize a Mobile OS?

    Thanks in advance.
  • dgz - Friday, July 23, 2010 - link

    To answer Q3 :)

    "VMware to Bring Virtualization to Mobile Phones, Enabling a Host of Benefits for Handset Vendors, Corporations and Mobile Phone Users"

  • Shadowmaster625 - Friday, July 23, 2010 - link

    Am I the only one who is noticing that Dailytech's comments no longer load? Well obviously they must load for someone, because it says there are comments. But they sure as hell don't load for me!
  • spddemon - Friday, July 23, 2010 - link

    I really wished VMware would offer a clustered file system option.

    VMware implements HA for host server redundancy, but it does nothing for redundancy at the SAN level. please please please add support for a clustered file system!! and yes, i do have redundant controllers, but that only works in some situations...

    a syslog function in the vCenter server would be great too.

    more control over update manager would be nice also. I really do not need iTunes patches.. lol
  • dilidolo - Friday, July 23, 2010 - link

    VMFS is a cluster file system.
    SAN level redundancy is storage vendor's job.
    Update Manager 4.1 removes guest patches, but even with older version of WUM, YOU configure what you want to patch. If you don't want guest patches, don't select it.
  • spddemon - Friday, July 23, 2010 - link

    VMFS is a cluster file system but it is not a CLUSTERED file system. Meaning you can't mirror san LUNs. This is not a storage vendor's sole responsibility (not very many storage vendor's offered a clustered filesystem option or a way to mirror a LUN that wouldn't require a manual reconfiguration to use the mirrored LUN), this why veritas offers a clustered file system. If VMware would support this file system one problem would be eliminated, but not all problems.

    I think you misunderstood my comment about update manager. I want a simple interface so that I can select what updates are applicable. Meaning, I still want the functionality, but not all the updates that are currently bundled. IE, i want MS and Adobe updates but I dont want iTunes.

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