Welcome!

Microsoft Cloud Authors: Yeshim Deniz, Janakiram MSV, Andreas Grabner, Stackify Blog, Liz McMillan

Related Topics: Microsoft Cloud

Microsoft Cloud: Article

Using MVS2005 with VS.NET

Better use of server capacity

Microsoft Virtual Server 2005 (VS2005), a new addition to the Microsoft Server family, emulates physical hardware to create multiple independently operating environments or virtual machines (VMs).

This article reviews portions of a C# application leveraging the VS2005 API. We will get you started with VS2005 here. The complete application code demonstrates one of the more interesting aspects of VMs: differencing hard drives. These drive disks allow you to toggle a VM from one configuration to a different configuration and back. This capability is especially useful for software testing and verification, where hardware resources are limited.

VS2005 is amazingly powerful but also adds a new level of complexity to server management. The VS2005 background and code provided in this article are just the tip of the iceberg to get you started. Take some time to work with virtualization. You'll quickly see how easily virtualization can benefit your organization.

Virtual Server Background
A full introduction to VS2005 could fill a book. The objective of this article is not to overwhelm you with details, but to show you how to write a simple interface program to VS2005 that does useful work. Before diving into code, some brief background on virtualization is necessary.

Virtualization enables a single physical server, or host, to be partitioned into many independently operating virtual servers. As depicted in Figure 1, the VS2005 software emulates the disk, network, keyboard/video/ mouse, processor, and memory needed to create a server. Each server is totally isolated from the others with no visibility into other VMs running on the same host. The virtualization software governs resource usage to ensure that one VM does not consume all of the host's CPU capacity.

It is important to distinguish between hosts and VMs for VS2005 compatibility. The host that runs the virtualization software must be running Windows Server 2003 (Windows XP works but is not "supported"). The VMs run a broad range of operating systems, including most flavors of Linux, DOS, Novell, Windows NT, and recent Windows releases but Microsoft will only support Windows. Microsoft, in fact, intends for VMs to become the primary supported platform for Windows NT.

What Makes Virtualization Compelling?
Virtualization is compelling because of the increased efficiency and control it brings to the physical server data center. Our company, Surgient, Inc., is an on-demand enterprise software company whose applications automate software sales, marketing, training, and testing processes. Surgient has been using virtualization platforms since 2001 as early beta testers of first-generation virtual server products. During that time, we have deployed over a thousand hosts and uncountable VMs. If you've experienced the Microsoft Visual Studio.NET hands-on trial, then you've used the Surgient demo management product and you've also used a VM! The VMs powering that site have served over 100,000 demos of VS.NET.

From the beginning, we recognized that VMs were fundamentally different and much more flexible than physical servers. The host's APIs enable programmatic control to manage the virtual servers. The price of this flexibility is additional planning and management of data center operations.

On a virtualization host, servers compete for limited amounts of memory (RAM), processor (CPU), and storage (disk). VS2005 VMs, like physical servers, need sufficient RAM to operate. They block out their full memory footprint on the host. You can, however, release a VM's memory by turning off the VM, which enables you to maintain more VM configurations than you can concurrently run.

These idle virtual images voraciously consume large amounts of disk. This means that a typical host may not have enough space to store many idle 4-10 GB virtual image files. VS2005 partially solves this problem by allowing VMs to chain image files into differencing layers that share a common base image.

The VS2005 differencing layer technology is called differencing disks (undo drives are a variant of differencing disks). This technology enables you to create a base image of the operating system and then install applications into a difference disk layer. A single base image can then be used by several VMs that each have a unique differencing disk.

Virtualization Example
Our sample scenario is a code development and testing environment for a three-tier application. The host server is a dual-processor server with 2GB of RAM and 120GB of RAID 5 disk. The proposed demo application must support both SQL Server and Oracle, each of which requires at least 1GB of RAM for testing. How can we use VS2005 to test the application in all its permutations using only the host server?

Memory is the obvious contention point. Of the available 2GB on the host, one quarter is reserved as overhead for the host operating system and VS2005, leaving just 1.5GB for the three application tiers. Since the databases each require 1GB, the entire application will just barely run on the host. To test both database platforms, we will have to keep one turned off while we are testing the other. Toggling the servers will keep our RAM use within the limits of the host.

Storage is a less obvious but equally serious challenge. Assuming 100GB available of the 120GB total should give ample room to store VM disk files. If we assume 10GB per VM, then we could store 10 VMs. Ten quickly drops to five if we plan to keep one archive copy of each VM.

Differencing disks provide the solution to both these issues. Our database server requires a 4GB Windows 2003 base image and two distinct differencing disks (SQL at 4GB and Oracle at 6GB). Without differencing, the two servers would consume 18GB of disk. Sharing the base image uses just 14, saving 4GB of disk. It is not necessary to archive the shared base because it does not change. We do, however, want to archive each differencing disk. The total storage is 24 GB, down from 36 GB without the use of differencing disks (see Figure 2).

Toggling the VM power states and working with shared base images addresses the resource limitations of the host.

Programming Virtualization Control
To use our testing environment, we must create a small .NET application that toggles between server configurations by changing both the VM's power state and its differencing disk configuration.

The C# sample application will provide the following features:

  1. Create a VM with appropriate components, including differencing and undo drives
  2. Manage the VM's power (Start and Stop)
  3. Change the disk configuration of an existing machine
  4. Simple user interface
This article focuses on key VS2005 interfacing points in the application. The entire program is available online at www.surgient.com/dndjsamplecode.

Before the program can run, it needs a reference for the VS2005 API. VS2005 provides a COM interface and requires a .NET Interop to use it. Visual Studio creates the Interop automatically when we add Microsoft Virtual Server from the COM Components tab from the Tools...Add/Remove Toolbox Items menu. This process will add the using Microsoft.VirtualServer.Interop reference to the code.

In addition to referencing the COM Interop, VS2005 requires COM security to enforce access control. Our sample application includes a dedicated class, COMServices, to provide this critical initialization. Your VS2005 application must include this or similar code. A call to COMServices. Initialize() is all that is needed before we can start using the VS2005 API.

The VS2005 API has two primary categories of functions. The first category controls the virtualization platform on the host, while the second controls states and attributes of individual VMs. The interface to the host is created by instantiating a new VMVirtualServerClass object. Once this object exists, it is possible to create VMVirtualMachine objects by either creating new VMs using CreateVirtualMachineVM or getting a reference to an existing VM using FindVirtualMachine.

The example application calls the host object "vs" for Virtual Server. Here is the code to attach to the host API:

VMVirtualServerClass vs = new VMVirtualServerClass();

Creating a Virtual Machine
The first step in creating a VM is deciding where to store the multigigabyte virtual disk files that store the data of the VM's hard drives. The VS2005 default is to bury the files deep in the Documents and Settings directory tree, which can cause serious issues on systems with multiple partitions as the largest files default to the operating system's partition. Change the default path for VMs from the VS2005 Web interface in the Virtual Server...Server Properties section. The VMs are stored in directories under the default virtual machine configuration folder. In this example, the host will store VMs on the second partition (d:) in the "vms" subdirectory.

Creating a VM is a multistep process. The basic CreateVirtualMachine method only creates a VM stub. The VM's RAM, disk, and network must be configured before it is usable. However, you cannot just attach disk and network to a VM; you must "install" virtual devices before you can attach media to them. Specifically, you must add a network adapter to your VM before you can attach it to the network and you must specify which IDE or SCSI ports you are using when you attach drives.

The first step is to create the VM stub. The application calls the VM object vm. Here is the code requesting the host object to create a VM:

VMVirtualMachine vm = vs.CreateVirtualMachine("vm01","d:\vms\vm01");

With the VM stub, it is possible to configure the VM's properties. Memory is the easiest to configure:

vm.Memory = 256;

Attaching a hard drive requires an existing virtual hard disk (VHD) file. You can use an existing one or create one dynamically. VHD files are configured to a maximum possible size and expand dynamically as data is added. The maximum size is specified in megabytes, so the code sample uses a 1K multiplication to improve readability. Here is how the host object is told to create a VHD file:

vs.CreateDynamicVirtualHardDisk("d:\vms\vm01.vhd", 16 * 1024)

Instead of creating a new disk (shown above), you can add a differencing disk to an existing hard disk. A differencing disk inherits the maximum size from its parent and also stores the parent's location in its header. You must supply both a unique disk name and the parent disk when you create a difference disk:

vs.CreateDifferencingVirtualHardDisk("d:\vms\vm02.vhd","d:\vms\parent.vhd");

Once the disk file exists, it can be attached to the VM by selecting a bus (IDE or SCSI) and the bus address. If the disk is a differencing disk, only the difference disk file is provided for connection. The parent disk is not programmatically connected because the difference disk already has the reference location for its parent disk. In this example, VS2005 will connect the drive at address IDE 0:0:

vm.AddHardDiskConnection("d:\vms\vm01.vhd", VMDriveBusType.vmDriveBusType_IDE, 0, 0);

Undoable mode is an important VS2005 feature because it allows you to maintain a working session for your server. When using undoable drives, you can maintain, commit, or discard the working session. There is minimal performance impact for this feature, and it eliminates the time wasted recovering or rebuilding server environments. Undoable mode is an attribute of the VM and applies to all drives:

vm.undoable = true;

Connecting the new network adapter to the correct host network is more challenging. The result is that the attached adapters are available as a NetworkAdapters array on the VM object. To create the network adapter for the VM:

vm.AddNetworkAdaper();

When installed, VS2005 automatically creates a virtual network for each physical host network interface card (NIC) and an extra "internal" network that can be shared between VMs but is not externally connected. Virtual networks may be created or added from the Web interface in the Virtual Networks section. The host object offers an array of VirtualNetworks. Connect a VM to a network by providing a reference to the desired host network with AttachToVirtualNework method for an adapter:

vm.NetworkAdapters[1].AttachToVirtualNetwork(vs.VirtualNetworks[0]);

Managing VM Power
VS2005 allows absolute control over a VM's power, including a saved state that releases a VM's memory and CPU resources. Suspend is useful because the VM immediately resumes work when restarted, avoiding an operating system reboot.

Basic power management uses the VM's Startup and TurnOff methods. These are not advised for most cases. TurnOff is dangerous because it does not gracefully shutdown, and Startup does not wait for the start before returning control.

To provide a graceful shutdown, the "Virtual Machine Additions" must be installed on the VM's GuestOS - Microsoft's name for the operating system running on the VM. VS2005 prompts you for the Additions in the Web interface. Once the additions are installed, you first check the CanShutdown property from the VM's GuestOS attribute:

If (vm.GuestOS.CanShutown vm.GuestOS.Shutdown();

Waiting for start or shutdown completion requires asynchronous calls to the VS2005 interface. Many VS2005 methods return a VMTask object that can be used to monitor task completion:

VMTask vt = vs.GuestOS.Shutdown();
if (vt !=null) vt.WaitForCompletion(-1);

Going Forward
Programming helps you unlock and automate some of the most powerful features of Microsoft Virtual Server 2005. This article covered key points to consider about using and programming Virtual Server. The complete sample application provides additional context and more features, including switching a VM's differencing disk as discussed in the example scenario. We believe that virtualization technology can radically improve the way you use server capacity and hope this article takes you a step closer to that realization.

More Stories By Rob Hirschfeld

Rob Hirschfeld, cofounder and chief architect at Surgient Inc., is responsible for evolving and driving the architecture of Surgient applications. Rob has 15 years' experience in software design and systems integration with an emphasis on applications and particularly the deployment of distributed, Web-integrated applications. he holds degrees in engineering from Duke University and Louisiana State University.

More Stories By Richard Cardona

Richard Cardona, principal engineer at Surgient Inc., is responsible for providing a platform interface to virtual computing resources. Richard has developed software using virtualizaiton technologies since 1988 in various cross-platform environments and most recently with VMware GSX and ESX, and Microsoft Virtual PC 2004 and Virtual Server using the Microsoft .NET Framework.

Comments (1) View Comments

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


Most Recent Comments
lawrence hordy 01/18/05 01:06:39 PM EST

i see a 3d spreadsheet emulating a 3d array of strings == done in RPG or RPG2 == done IN CALCSTAR for a Z80 with CPM/80
== done in other antique spreadsheets for old operating systems

@ThingsExpo Stories
"We provide IoT solutions. We provide the most compatible solutions for many applications. Our solutions are industry agnostic and also protocol agnostic," explained Richard Han, Head of Sales and Marketing and Engineering at Systena America, in this SYS-CON.tv interview at @ThingsExpo, held June 6-8, 2017, at the Javits Center in New York City, NY.
SYS-CON Events announced today that Calligo, an innovative cloud service provider offering mid-sized companies the highest levels of data privacy and security, has been named "Bronze Sponsor" of SYS-CON's 21st International Cloud Expo ®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Calligo offers unparalleled application performance guarantees, commercial flexibility and a personalised support service from its globally located cloud plat...
Internet of @ThingsExpo, taking place October 31 - November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 21st Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago. All major researchers estimate there will be tens of billions devic...
"The Striim platform is a full end-to-end streaming integration and analytics platform that is middleware that covers a lot of different use cases," explained Steve Wilkes, Founder and CTO at Striim, in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
"We are focused on SAP running in the clouds, to make this super easy because we believe in the tremendous value of those powerful worlds - SAP and the cloud," explained Frank Stienhans, CTO of Ocean9, Inc., in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
DX World EXPO, LLC., a Lighthouse Point, Florida-based startup trade show producer and the creator of "DXWorldEXPO® - Digital Transformation Conference & Expo" has announced its executive management team. The team is headed by Levent Selamoglu, who has been named CEO. "Now is the time for a truly global DX event, to bring together the leading minds from the technology world in a conversation about Digital Transformation," he said in making the announcement.
SYS-CON Events announced today that DXWorldExpo has been named “Global Sponsor” of SYS-CON's 21st International Cloud Expo, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Digital Transformation is the key issue driving the global enterprise IT business. Digital Transformation is most prominent among Global 2000 enterprises and government institutions.
SYS-CON Events announced today that Datera, that offers a radically new data management architecture, has been named "Exhibitor" of SYS-CON's 21st International Cloud Expo ®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Datera is transforming the traditional datacenter model through modern cloud simplicity. The technology industry is at another major inflection point. The rise of mobile, the Internet of Things, data storage and Big...
"MobiDev is a Ukraine-based software development company. We do mobile development, and we're specialists in that. But we do full stack software development for entrepreneurs, for emerging companies, and for enterprise ventures," explained Alan Winters, U.S. Head of Business Development at MobiDev, in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
"We've been engaging with a lot of customers including Panasonic, we've been involved with Cisco and now we're working with the U.S. government - the Department of Homeland Security," explained Peter Jung, Chief Product Officer at Pulzze Systems, in this SYS-CON.tv interview at @ThingsExpo, held June 6-8, 2017, at the Javits Center in New York City, NY.
While the focus and objectives of IoT initiatives are many and diverse, they all share a few common attributes, and one of those is the network. Commonly, that network includes the Internet, over which there isn't any real control for performance and availability. Or is there? The current state of the art for Big Data analytics, as applied to network telemetry, offers new opportunities for improving and assuring operational integrity. In his session at @ThingsExpo, Jim Frey, Vice President of S...
SYS-CON Events announced today that DXWorldExpo has been named “Global Sponsor” of SYS-CON's 21st International Cloud Expo, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Digital Transformation is the key issue driving the global enterprise IT business. Digital Transformation is most prominent among Global 2000 enterprises and government institutions.
In his opening keynote at 20th Cloud Expo, Michael Maximilien, Research Scientist, Architect, and Engineer at IBM, discussed the full potential of the cloud and social data requires artificial intelligence. By mixing Cloud Foundry and the rich set of Watson services, IBM's Bluemix is the best cloud operating system for enterprises today, providing rapid development and deployment of applications that can take advantage of the rich catalog of Watson services to help drive insights from the vast t...
SYS-CON Events announced today that EnterpriseTech has been named “Media Sponsor” of SYS-CON's 21st International Cloud Expo, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. EnterpriseTech is a professional resource for news and intelligence covering the migration of high-end technologies into the enterprise and business-IT industry, with a special focus on high-tech solutions in new product development, workload management, increased effic...
SYS-CON Events announced today that Massive Networks, that helps your business operate seamlessly with fast, reliable, and secure internet and network solutions, has been named "Exhibitor" of SYS-CON's 21st International Cloud Expo ®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. As a premier telecommunications provider, Massive Networks is headquartered out of Louisville, Colorado. With years of experience under their belt, their team of...
SYS-CON Events announced today that Cloud Academy named "Bronze Sponsor" of 21st International Cloud Expo which will take place October 31 - November 2, 2017 at the Santa Clara Convention Center in Santa Clara, CA. Cloud Academy is the industry’s most innovative, vendor-neutral cloud technology training platform. Cloud Academy provides continuous learning solutions for individuals and enterprise teams for Amazon Web Services, Microsoft Azure, Google Cloud Platform, and the most popular cloud com...
SYS-CON Events announced today that Cloudistics, an on-premises cloud computing company, has been named “Bronze Sponsor” of SYS-CON's 21st International Cloud Expo, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Cloudistics delivers a complete public cloud experience with composable on-premises infrastructures to medium and large enterprises. Its software-defined technology natively converges network, storage, compute, virtualization, and ...
SYS-CON Events announced today that CHEETAH Training & Innovation will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct. 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. CHEETAH Training & Innovation is a cloud consulting and IT training firm specializing in improving clients cloud strategies and infrastructures for medium to large companies.
SYS-CON Events announced today that Datanami has been named “Media Sponsor” of SYS-CON's 21st International Cloud Expo, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Datanami is a communication channel dedicated to providing insight, analysis and up-to-the-minute information about emerging trends and solutions in Big Data. The publication sheds light on all cutting-edge technologies including networking, storage and applications, and thei...
The current age of digital transformation means that IT organizations must adapt their toolset to cover all digital experiences, beyond just the end users’. Today’s businesses can no longer focus solely on the digital interactions they manage with employees or customers; they must now contend with non-traditional factors. Whether it's the power of brand to make or break a company, the need to monitor across all locations 24/7, or the ability to proactively resolve issues, companies must adapt to...