A Unique Hypervisor: Microsoft Azure and Hyper-V Cloud Computing

Microsoft has included the Hyper-V hypervisor in Microsoft Server 2008 (code-named Viridian); Hyper-V is also available in a free, reduced-function stand-alone version. However, Hyper-V, which provides partition-level isolation, is not the basis for the Hypervisor in Microsoft Azure. That was written, like the rest of Azure, from the ground up and is particularly optimized for multitenancy.

The Windows Azure Hypervisor is tightly optimized with the Windows Azure kernel. However, Microsoft has stated that some of the features of the Azure Hypervisor will ultimately make their way into the next version of Hyper-V. For example, Second-level Address Translation will be available in Hyper-V v2.0. This concept is explained in U.S. Patent 7,428,626, invented by Rene Antonio Vega and assigned to Microsoft:

A method of performing a translation from a guest virtual address to a host physical address in a virtual machine environment includes receiving a guest virtual address from a host computer executing a guest virtual machine program and using the hardware oriented method of the host CPU to determine the guest physical address. A second level address translation to a host physical address is then performed. In one embodiment, a multiple tier tree is traversed which translates the guest physical address into a host physical address. In another embodiment, the second level of address translation is performed by employing a hash function of the guest physical address and a reference to a hash table. One aspect of the invention is the incorporation of access overrides associated with the host physical address which can control the access permissions of the host memory.

Microsoft released 20,000 lines of device-driver source code for virtualizing Linux over Windows. Some say that Microsoft made the move to rectify a violation of the open source General Public License v2. “The driver had both open-source components which were under GPL, and statically linked to several binary parts. The GPL does not permit mixing of closed and open source parts, so this was an obvious violation of the license,” said Stephen Hemminger, a principal programmer with open-source networking firm Vyatta.

Managing a Virtualized Infrastructure
Cloud management challenges are illustrated below

Managing a farm of physical servers, each running multiple virtual servers, is a management challenge that cries out for software solutions. We illustrate this with ConVirt 2.0, which is an open source solution. But it’s a rapidly growing area, and new products are announced frequently.

ConVirt 2.0 allows you to centrally monitor and configure your Xen and KVM virtual machines and proactively manage your virtualized infrastructure. The company’s Web site claims that, “Armed with a consolidated view across all your Xen and KVM virtual machines, you can keep apprised of server utilization and easily respond to changes in application demand by reallocating reallocating resources.”

Challenges of cloud management (courtesy DMTF.org).

Challenges of cloud management (courtesy DMTF.org).

ConVirt 2.0 Centralized Monitor for Xen and KVM. The data center– level configuration view provides detailed information about operating systems, storage, and networks resources in your environment. (Licensed under the GNU Free Documentation License.)

Centralized Monitor for Xen and KVM

Monitoring and Management
Knoa, a commercial vendor, offers Virtual/Cloud Experience Manager
(VCEM), an off-the-shelf product designed to monitor and manage real end-user experience for enterprise applications that are running in virtualized environments, delivered via SaaS, or provisioned via cloud computing. VCEM’s features include:

  • Dynamic Benchmarking, which enables the IT organization to compare system performance prior to the change with system performance before and after each wave of infrastructure transition. Dynamic Benchmarking is available for all system performance metrics including transaction response times, system errors and utilization.
  • Comprehensive Threshold Alerting, which allows IT organizations to create and manage alerts based upon established Service Level Agreements. Alerts can be delivered via e-mail or integrated into existing performance management consoles to provide the IT team with a “single pane of glass” for performance management.
  • Dynamic Base-lining, which allows IT organization to monitor when any performance metric (response time, quality or utilization) varies from short or long-term trends. Dynamic base-lining directly attacks the difficult issue of ensuring no performance degradation for the thousands of transactions for which meaningful SLA thresholds have not been set.
  • Advance Root Cause Analysis, which allows the IT Operations team to evaluation the impact of end-user behavior and desktop resources and conditions on any performance anomaly.

Commercial Virtualization Offerings
We can’t do justice to a discussion of virtualization without discussing Citrix and VMware.

Citrix has been catching a wave.Founded in 1989 by Ed Iacobucci, a former developer for IBM, Citrix’s name is a portmanteau (blended word) of Citrus, the company’s original name, a tribute to its headquarters in Coral Springs, Florida, and UNIX. So right away, you know that they are into open source.

Citrix was an early pioneer in virtualization for PC architecture, Win- View, which provided remote access to DOS and Windows 3.1 applications on a multi-user platform. Microsoft agreed to license Citrix technology for Windows NT Server 4.0, resulting in Windows Terminal Server Edition, and Citrix agreed not to compete with a product of its own. However, it could (and did) offer extensions, which it initially called Metaframe XP and Presentation Server.

The product, now called XenApp, provides application virtualization and application delivery. Citrix XenDesktop is a desktop virtualization and virtual desktop infrastructure (VDI) solution that delivers a complete Windows desktop experience as an on-demand service to any user, anywhere. In the virtual desktop market, Citrix and VMware are the main competitors.

Citrix’s XenServer, discussed below, provides server platform virtualization. First-generation VDI solutions were useful only to a narrow set of users, primarily those working all day using a small number of corporate applications.

Today, whether users are task workers, knowledge workers or mobile workers, XenDesktop can quickly and securely deliver individual applications or complete desktops while providing a high-definition user experience. Citrix calls its delivery technology FlexCast, and it enables IT to deliver any type of virtual desktop, on any device. The most important benefits of the Citrix Xen Desktop are reduced administration and management costs.

Founded in 1998, VMware is the 800-pound gorilla in the virtualization room, with more than $2 billion in revenue. It offered its first virtualization platform (for x86 systems) in 1999. VMware was acquired by EMC in 2004, and partially spun-off from EMC in 2007, but EMC still overwhelmingly controls it.

Since parent EMC is a hardware vendor, primarily serving larger enterprises, VMware not surprisingly has private, secure data centers in its DNA, and has been going, as they say about themselves, “all in” on Private clouds. It is a founding sponsor of PrivateCloud.com, an industry destination for news, resources, and conversation on enterprise cloud computing that’s worth a visit. However, they are very active (through partners) in the public cloud space as well.

VMware has three offerings. vSphere is VMware’s offering for a private cloud solution and the current incarnation of its crown jewels. VMware ESXi is a free hypervisor solution somewhat comparable to Citrix XenServer, while VMware Server is a hosted solution. compares VMware offerings:

VMware’s special spices are a large variety of Virtual Appliances. VMware uses the term Virtual Appliance to describe the premade image that is similar to the Amazon Machine Image (AMI), but goes a step further by allowing for preinstalled, pretested, packaged software from the VMware Virtual Appliance Marketplace. These may be highly specific. For example, the AllardSoft Secure Filetransfer Virtual Appliance is installed on a server in your own facilities to send big files securely to customers, clients, or other staff members. It integrates with your existing Active Directory or LDAP infrastructure to further assist with the deployment.It’s but one of hundreds of Marketplace offerings.

Xen desktop technology.technology. Licensed under the GNU Free Documentation License.

Xen desktop technology.technology. Licensed under the GNU Free Documentation License.

Comparison of VMware offerings. © VMware, Reproduced by Permission

Comparison of VMware offerings. © VMware, Reproduced by PermissionComparison of VMware offerings. © VMware, Reproduced by PermissionComparison of VMware offerings. © VMware, Reproduced by Permission

At this writing, VMware itself is not in the public cloud business. It partners, as we shall discuss, with many leading cloud service providers. Paul Maritz, who retired from Microsoft after 14 years, ulminating as group vice president of platform strategy, is president and CEO of VMware, and Tod Nielsen, another senior Microsoft development executive, is its chief operating officer. Since these well-regarded folks spent significant parts of their careers at Microsoft, software is obviously in their DNA, but they are more used to selling software-in-a-box and per-seat licenses than they are to selling metered pay-as-you-go cloud computing.

Perhaps for this reason, VMware has partnered with third parties who provide external cloud infrastructure as a service that can integrate seamlessly with the internal cloud that VMware will be only too happy to sell you. vCloud Express is VMware’s Infrastructure as a Service (IaaS) offering delivered by VMware’s third-party service provider partners. It provides reliable,on-demand, pay-as-you-go infrastructure that ensures compatibility with internal VMware environments and with VMware Virtualized™ services. VMware’s partners include:

  • Bluelock
  • Hosting.com
  • Terremark

Of these, Terremark Worldwide, Inc. is the most established VMware partner. Founded in 1982, Terremark offers Infrastructure as a Service and owns and operates purpose-built datacenters in the United States, Europe, and Latin America, and access to massive and diverse network connectivity from more than 160 global carriers. VMware holds a six percent equity interest in Terremark, which provides carrier neutral colocation, managed services, and exchange point services to approximately 1,300 customers worldwide including many government entities from three highly specialized data centers, or Network Access Points (NAPs), that were purpose-built and have been strategically located to provide security, reliability, power availability and connectivity.

So far, the market is with VMware, in the sense that there are more private than public clouds. However, public clouds are growing quickly and maturing rapidly. As astute observers of the IT scene and as former Microsoft executives, VMware’s management are well aware of three things:

  1. Microsoft has, since its founding, derived substantially all of its revenue from software licensing,
  2. Microsoft has made a huge bet on public cloud computing, which is our subject for the next chapter, and
  3. Microsoft is under substantial pressure from free open source software. It will be interesting to look back in a few years to see if the largely proprietary “software only” strategy of the dean of virtualization will prove to be the winning strategy.

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