Virtual Dedicated Servers – An Overview

Virtual Dedicated Servers – An Overview

Microsoft CorporationPublished: February 2007

AbstractMicrosoftÒ Virtual Server 2005 R2 is a cost-effective and well-supported server virtualization technology for the Windows Server System™ platform. As an expansion of the services which can be made available to hosters, Virtual Server presents an opportunity for the delivery of flexible and scalable offerings to the market. Virtual Server increases hardware utilization and allows the hoster to improve the return on investment made in physical hardware. In conjunction with Windows Server™ 2003, Virtual Server provides a virtualization platform that runs most major x86 operating systems in a guest environment, and is supported by Microsoft as a host for Windows Server operating systems and Windows Server System applications. Virtual Server 2005 R2 has a comprehensive COM API which, in combination with the Virtual Hard Disk (VHD) format and support for virtual networking, provides administrators complete scripted control of portable, connected virtual machines. Virtual Server enables easy automation of deployment, and ongoing change and configuration. The information contained in this document represents the current view of Microsoft Corporation on the issues discussed as of the date of publication. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of

Virtual Dedicated Servers – An Overview

Microsoft, and Microsoft cannot guarantee the accuracy of any information presented after the date of publication.

This White Paper is for informational purposes only. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS DOCUMENT.

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All other trademarks are property of their respective owners.

Virtual Dedicated Servers – An Overview

ContentsIntroduction............................................................................................................................................ 3

What is Virtual Server........................................................................................................................... 3

Virtual Dedicated Hosting Scenarios.....................................................................................................3

Virtualization Benefits........................................................................................................................... 5

Architecture Planning............................................................................................................................ 6

Network considerations......................................................................................................................... 6

Authentication considerations...............................................................................................................7

Hardware considerations...................................................................................................................... 7

Recommended configuration (supporting virtual dedicated hosting).................................................7

Windows 2003 and Virtual Server.....................................................................................................7

64Bit Support..................................................................................................................................... 8

Virtual Server Setup and Configuration...............................................................................................9

Installation and options......................................................................................................................... 9

Virtual Server Scalability.....................................................................................................................10

Key scalability elements...................................................................................................................... 10

Recommendations for virtual dedicated hosting scenarios.................................................................10

Memory........................................................................................................................................... 11

Disk................................................................................................................................................. 11

Network........................................................................................................................................... 11

Provisioning Automation.....................................................................................................................13

Automation tips and tricks...................................................................................................................13

Physical Server ADS imaging..........................................................................................................13

Virtual Server image library.............................................................................................................13

Provisioning Automation and Orchestration....................................................................................13

Virtual Server COM interface..............................................................................................................14

Monitoring and Management...............................................................................................................15

MOM Virtual Server Support pack......................................................................................................15

Key Features in the Virtual Server Management Pack....................................................................15

Service Provider Licensing.................................................................................................................16

Licensing model.................................................................................................................................. 16

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Virtual Dedicated Servers – An Overview

Useful Links.......................................................................................................................................... 17

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Virtual Dedicated Servers – An Overview

Introduction

What is Virtual Server

Microsoft Virtual Server is a virtualization product that provides emulation of x86 hardware in software. Virtual Server supports the concept of “guest” instances of an emulated hardware system. Each system is isolated from others running on the host and can run “most” modern x86-based operating systems (Windows, Linux, Solaris, etc)

Virtualization is often used to optimize processor utilization as many server applications do not fully tax a modern server. It has been seen in recent studies that some servers, while requiring high processor speeds at peak times, are actually idle for a considerable amount of their lives.

Today, hosting service providers are using virtualization technology from a range of vendors, including Microsoft. One common application of virtualization in the hosting business is the advent of virtual dedicated hosting offering

“Microsoft’s virtualization strategy contrasts with current alternatives for virtual machine management, which tend to be complex, expensive and require specialized skills. We look at virtualization as key technology to help customers achieve self-managing dynamic systems. Across the platform, operating system, applications and management layers we’re delivering functionality and capabilities that enable our customers to significantly reduce operating costs, drive up server utilization and achieve better ROI through full featured virtualization solutions.”

- Bob Muglia, Senior Vice President, Server and Tools Business at Microsoft.

Virtual Dedicated Hosting ScenariosToday there is more pressure than ever on hosters to provide greater levels of feature and functionality at ever- reducing price points. There is also strong demand for provisioning of service over a reduced period in order to fulfill a specific short-term requirement, whether that be as a test–bed for development, a web-site for a marketing promotion, or as the central point for a virtual project team. Often a six-month hosting contract for a dedicated server system would not cover the costs of the hardware in most cases; and, coupled with the demand for the latest technologies by the customer base, this may leave the hoster with ‘old’ equipment which may need to be updated before re-sale.

Virtualization as a technology can address the requirements for shorter term and lower costs dedicated environments and still enable hoster to derive a good return on their hardware investment.

The use of Virtualization technology in the hosting industry can take many forms. One of the more prevalent scenarios is using virtualization to divide up a physical server into multiple virtual dedicated instances. This is often termed “VPS” or Virtual Private Server hosting. The common scenario in dedicated hosting is to provide a physical server of a certain specification that is connected to the internet. Management (typically via terminal services) is the responsibility of the subscriber. In virtual dedicated scenarios, the physical server is replaced with an “instance” of a virtual machine. The

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service provider typically provides a base OS configuration and the subscriber is responsible for management and operation remotely via terminal services.

Virtual dedicated hosting can take a number of forms, including:

Low-cost dedicated serversHosting customers require the levels of control over their environment gained through a dedicated server, but demand a lower price point for the facilities. Virtual Server allows the hoster to provide the ‘ownership’; of a dedicated server to the customer at a price point otherwise not achievable.

Proof-of-concept deploymentsThe customer needs to deliver a proof-of-concept for a product or solution without the overhead of hardware purchase. The use of virtualization enables the hoster to provide a fully configured network environment on a single server at no capital cost to the customer.

Business continuity management: IT administrators are always trying to find ways to reduce or eliminate downtime from their environment. Windows Server virtualization will provide capabilities for efficient disaster recovery to eliminate downtime. The robust and flexible virtualization environment created by Windows Server virtualization minimizes the impact of scheduled and unscheduled downtime.

Software test and development: One of the biggest areas where virtualization technology will continue to be relevant is the software test and development area to create automated and consolidated environments that are agile enough to accommodate the constantly changing requirements. Windows Server virtualization helps minimize test hardware, improve lifecycle management, and improves test coverage.

Performance and Service levels:

The dedicated hosting industry takes on many forms, with variables in price, performance, and management support. Virtual dedicated based hosting offering can include many of these same variables. One important variable in Virtual Dedicated hosting is the aspect of “guest” density. This is the ratio of guest operating systems relative to each physical server. The performance and scalability of each “guest” instance on a particular host is closely related to the number of guests and the workload that is active on each guest. Operators need to pay particular attention to both the load and the density of guest instances as they optimize a hosting offering.

This paper will make some recommendations and generalizations about hardware, performance, and density. Ultimately the service provider will need to evaluate the options and determine the best fit for the market they intend to serve.

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Virtual Dedicated Servers – An Overview

Virtualization BenefitsHosters today are under increasing pressure to deliver more value to their customers at ever reducing price points. Optimizing the use of physical IT assets is also becoming an imperative as data centers reach their capacity for power and space. Microsoft recognizes that this situation is common with dedicated server hosters the majority of whose customer servers run at very low utilization. Server utilization rates of less than 5 percent are not uncommon, and many customers usage rates fall into the 10-15 percent range. Many of these challenges, shared between server administrators and developers, can be addressed with the help of Microsoft’s virtualization solutions.

As a key part of any hosted server product strategy, Microsoft’s virtualization solution increases hardware utilization and enables hosters to rapidly configure and deploy new services while deriving the following key benefits:

Efficient use of hardware resources. By being separated from the underlying hardware, virtual servers, as hosted products, can be specified and marketed to suit the requirements of the hosters specific market space rather than, as is the case with dedicated server, being driven by the current technologies. Indeed advances in the physical server technologies make the virtualized environments, with the supporting machine isolation and resource management, more attractive to hosters due to the multi-tenant nature of the environment.

Enhanced administrative productivity and responsiveness. Microsoft Virtual Server provides easy integration into existing server management tools, such as System Center Operations Manager and sophisticated tools such as System Center Virtual Machine Manager (SCVMM) facilitates management of Windows virtual machines. The ability to consolidate workloads in a hardware agnostic environment and an integrated physical and virtual IT management framework enables administrators to lower operational costs and create more agile data centers.

Better-supported server virtualization solution. Virtual Server is extensively tested and supported by Microsoft in conjunction with its server operating systems and applications. Hence Virtual Server is a well-supported virtualization solution both within Microsoft and across the broader ISV community. The use of a common virtual hard disk (VHD) format ensures investment protection for all the virtual machines created for Virtual Server with a transparent migration path to Microsoft virtualization.

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Architecture Planning

Network considerationsVirtual Server 2005 supports up to 4 Virtual Network Interface Cars (NIC). Ideally, the Virtual Networks should be setup with a Backend, Frontend structure. The two Virtual Networks should be attached to dedicated physical network adapters on the Virtual Server Host. Multiport NICs can be a good choice for the host server.

Note: Networking of the guest operating systems can and should be highly isolated from the host system. Virtual server requires no specific protocol binding to the NIC on the host adapter (meaning you can clear all checkboxes in the host adapter that will be dedicated to the guest(s). The host adapter is mapped to a guest in the virtual server web based administration tool. A typical configuration would use a host with 3 active NICs where the 1st NIC is bound to the host, and the remaining NICs are bound to dedicated Virtual Local area Networks (vlans) for both frontnet and backnet configurations.

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Authentication considerationsWe recommendthat both the host computer and guest instances be a member of a Microsoft Windows Active Directory domain. The domain is used to establish a single source for authentication and containment of user accounts (both administrative and local guest administrative accounts). Management of servers within a domain is a good foundation for the use and application of group policies. More information about how Active Directory can be used for centralized management can be found in the Microsoft Solution for Windows Based Hosting version 4.0 or later.

Hardware considerations

Recommended configuration (supporting virtual dedicated hosting)

Hosting servers on a Virtual Server platform requires high availability and maximum performance for the host server, the following Virtual Server Host hardware configuration achieves both of these requirements:

CPU: (2) 64-bit Dual-Core Intel Xeon ProcessorsMemory: 8-32GB (dependent on guest density and requirements)Operating System: Windows 2003 Standard x64 EditionNIC: (2) Gigabit network cards Storage: 500GB (RAID 10)

(Note: the recommendation of Windows 2003 x64 Edition. 64bit Windows provides greater scalability when the 64bit version of virtual server R2 is used. The 32bit and 64bit versions are the same except that the 64bit version should provide greater performance for the guest instances. The 64bit version will only run 32bit guest operating systems)

Windows 2003 and Virtual Server

Virtual Server 2005 R2 running on Windows Server 2003 supports most Windows Server Catalog devices, providing customers with compatibility to run Virtual Server 2005 R2 on a wide range of hardware.

Virtual Guest hardware profiles include: Each virtual machine presents the same set of virtualized devices:

o A single Virtual Processor (ID based on the real processor).o Up to 3.6GB of system memory.

Virtual Server 2005 R2 can support up to 64GB of host memory. Host memory cannot be over-allocated to virtual machines. 440BX chipset. Adaptec 2940 PCI SCSI controller (up to 4 buses). S3 Trio64 SVGA (with 2D hardware acceleration). PXE boot support via Intel 21140 Ethernet adapter (up to four virtual NICs).

o A local virtual network connection does not need to be associated with a device.o Virtual machines can also be configured to have no virtual network connection.

IDE/ATAPI controller.

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Virtual Dedicated Servers – An Overview

o Legacy devices - keyboard, mouse, COM and LPT ports, CMOS, PIC, DMA, etc.

Virtual Server 2005 R2 supports both guest clustering between instances as well as host-to-host clustering for advanced scenarios. For more details, see the Virtual Server 2005 R2 Release Notes.

64Bit Support

Virtual Server 2005 R2 runs natively within an x64 Windows host operating system, providing customers not only with increased performance but also with more memory headroom for greater scalability.

The additional memory address space of 64-bit operating systems allow for more guest machines to be run on one host server:

• Virtual Server 2005 R2 running on 64-bit systems does not have a memory aperture limit.

Virtual Server 2005 R2 is supported by the following 64-bit host operating systems:

• Windows Server 2003 Standard x64 Edition

• Windows Server 2003 Enterprise x64 Edition

• Windows XP Professional x64 Edition

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Virtual Server Setup and Configuration

Installation and optionsSetting up Virtual Server consists of the following steps:

Install IIS. You must install the World Wide Web Service component of Internet Information Services (IIS) so that you can use the Administration Website to manage Virtual Server. For more information about installing IIS, see the documentation for IIS.

Install Virtual Server. There are two general configuration options for installing Virtual Server. You can use a single physical computer for both the Virtual Server service and the Website components, or you can use multiple computers, separating the Virtual Server service from the Website components. For more information about these options, see Installing the Administration Website. For information describing how to install Virtual Server on the physical computer, see Install Virtual Server. For more information about the Administration Website, see Open the Administration Website.

Add or create a virtual machine. You should add a virtual machine for each different operating system you want to run as a guest operating system. For information about how to add a virtual machine to Virtual Server, see Setting Up Virtual Machines for Virtual Server.

Add a guest operating system and Virtual Machine Additions. As appropriate, add a guest operating system and Virtual Machine Additions to your virtual machines. You can build a new operating system by using an ISO image of a boot CD, or you can use PXE boot functionality within the guest. For information, see Setting Up Operating Systems for Virtual Machines in Virtual Server .

Perform post-setup activities. As appropriate, performing any post-setup activities on the virtual machines, such as running sysprep.

Note:

Virtual Server can also be installed from the command prompt which supports both manual and unattended installation. For more information, see Installing Virtual Server from the command line.

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Virtual Server Scalability

Key scalability elementsThe scalability of one or more virtual guest instances is highly dependent on a number of factors. In this order, Memory, Disk, and Network tend to be the bottlenecks for performance. In terms of pure magnitude, Memory availability is a primary constraint for serving multiple guest instances. Memory utilization of guest machines is stacked, rather than shared. Meaning a system with 3 guests each using 1gb of ram each would require the host system to have a minimum of approximately 3.5gb of ram where 512mb of system memory is reserved for the host OS. In general, Windows will always run “better” with more memory, and service providers will need to balance available physical memory and the types of guests and offerings to be configured. Guest scalability can also be affected by overall disk performance; Windows can make heavy use of a paging file, and when multiple guests are contending for the same disk resource, performance may degrade. Separating guest instances (placement of the VHD) across multiple spindles or other disk/SAN interfaces can make a considerable impact on overall performance. Lastly, network performance can be a bottleneck, however in hosting scenarios, networking is much less of an issue for overall guest scalability (in trying to determine the maximum number of guest instances for a given hardware type).

Recommendations for virtual dedicated hosting scenariosThe following configuration is representative of scenarios currently in use by hosters.

Hardware:

Dual proc 64bit, Zeon 6gb of ram, dual nic, dual 300gb SATA

Guest density on the same hardware is one way to offer different levels of price / performance. Many hosters will use a fixed configuration for the hardware and then offer 2-3 levels of pricing where only the guest density is varied.

Example:

Value Hosting: $39/month, Windows 2003 Server Standard Edition, 512mb ram, shared with 8 guests total

Value Plus Hosting: $69/month, Windows 2003 Server Standard Edition, 1gb ram, shared with 4 guests total

Performance Hosting: $89/month, Windows 2003 Server Standard Edition, 2gb ram with 2 guests total

Note: Prices quoted are for example purposes only and do not reflect any recommendation on pricing.

There are a number of best practices available from the Virtual Server 2005 R2 Release Notes.

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Memory

Physical Address Extension (PAE) X86 should be enabled on the host operating system if it is appropriate to do so. PAE X86 allows the host operating system to access more than 4 gigabytes (GB) of physical memory. PAE X86 should not, however, be enabled on the virtual machines. Virtual machines can only access up to 3.6 GB of memory each; thus this technology is not necessary.

For more information about PAE X86, see "Enterprise Memory Architecture" at the Microsoft Web site, TechNet.

Disk

Under heavy workloads it is possible that the host operating system reports disk time-outs or excessive disk queue length. The best way to avoid this problem is to construct the local storage, use:

Multiple physical drive spindles

RAID to spread the access load over the spindles

Fast access disk types such as SCSI

Another option for storage is iSCSI. With iSCSI, the hardware needed for connecting servers to storage is less expensive and less complex than with the common alternative, Fibre Channel. By using iSCSI, you can minimize the amount you spend on hardware for connecting your servers to the storage they use.

iSCSI is not only less expensive than Fibre Channel, but is also much easier to configure, both when deploying new hardware and when reconfiguring after a hardware component has been replaced.

For further information on the use of iSCSI with Virtual Server , see Virtual Server 2005 R2 Release Notes.

It is also possible to use a storage area network (SAN) with virtual machines. Such implementations can, due to the nature of the storage specific protocol used by the SAN, be quicker than local disks. However, the traffic levels must be monitored to ensure a bottleneck does not occur at the Host Bus Adaptor. For further information on using SAN with Virtual Server , see Virtual Server 2005 R2 Release Notes.

Network

Virtual machines that require a high level of network activity can burden the physical network adapters on the physical computer. This in turn can make it difficult to connect to the host operating system or administer the host operating system using the network adapters. To alleviate this problem, we recommend that the physical computer be configured with two or more network adapters. One of the network adapters should be dedicated for use by only the host operating system. To do this, unbind the Virtual Machine Network service from this dedicated network adapter. You should unbind all network protocols, for example, Transmission Control Protocol/Internet Protocol [TCP/IP] except for the Virtual Machine Network service from all of the other network adapters that you will use for virtual machines. This will ensure that these network adapters are dedicated to Virtual Server networking.

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Provisioning Automation

Hosting scenarios often require efficient techniques for configuring hardware and software components. Various techniques are used to automate server provisioning processes. Virtual machines, in many cases, can be treated the same as physical hardware. Virtual Server guest instances support PXE boot for automating the boot and server build process. Most, if not all, tools that you use to manage physical systems today can be applied to virtualized guest instances.

Virtual servers, differ from physical servers in that all of the guest state is stored in a single VHD file. For this reason, other replication techniques can be employed for duplicating and personalizing guest instances.

Automation tips and tricksIn order to maximize the productivity of the hosting environment and minimize the time taken to bring new virtual servers live, the following tips may be handy:

Physical Server ADS imaging

By maintaining a standard ‘host’ system configuration the host OS can be imaged by using Microsoft Automated Deployment Service (ADS). This image would contain all of the required applications and clients to allow it to be deployed and personalized in the space of a few minutes, making it available for customer Virtual Server hosting. This process itself could be automated using the ADS API and driven by event triggers from Microsoft Operations Manager or other monitoring infrastructure for example.

Virtual Server image library

A collection of virtual machine images in vhd form could be kept on a storage source available to all of the physical host servers. The configuration of the images in the library would reflect the ‘products’ being sold by the hoster and would allow these to be deployed and personalized extremely quickly, providing the customer with an ‘instant’ result after a web-based purchase. It should be noted that instances based on a Windows OS should use the sysprep procedure for preparing the OS instance for duplication. A sysprep’d image will require that uniquely indentifying information such as the host name, and potentially IP address information be entered manually or through an automated process using an answer file. You can find out more information about sysprep from the documentation and utilities included on the Windows server boot CD.

Provisioning Automation and Orchestration

The Microsoft Solution for Windows based Hosting (WBH) provides information on how service providers can apply automation for fully automated provisioning flow. The solution includes information on the Microsoft Provisioning System (MPS).

MPS is a transaction-based engine that delivers a set of providers that enable actions on system components. Windows-based Hosting for Applications Windows-based Hosting for Applications, in addition to providing the reference architecture, ships with an SDK for MPS. MPS includes a wide

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variety of providers, including sample providers with source code. MPS is an orchestration engine that, along with the included providers has the capability to automate user and provisioning tasks, potentially with hundreds of discrete steps, into a single transaction.

MPS transactions are enabled through a modular design of providers. Providers are compiled code that speaks to services within the data center. The solution ships with over 20 base providers for enabling actions on components such as IIS, Active Directory, DNS, file system, and a generic script provider. The work performed by the provider components is orchestrated through MPF Named Procedures, which are grouped by functionality into Namespaces. Named Procedures are XML descriptions of the tasks necessary to provision a given service. Add User / Delete User, are examples of named procedures. Namespaces group Named Procedures by functionality and wrap them into Business Logic to complete the workflow needed to provision the service. Managed WebHosting and the Windows-Based Hosting Namespace are examples of Namespaces. ISV’s and service providers are free to develop custom providers to enable MPS to communicate with their code base and allow the interaction at the namespace layer with other providers.

For more information on MPS and the WBH solution see: http://www.microsoft.com/technet/serviceproviders/library4/default.mspx?mfr=true

The MPS SDK can be found at: http://www.microsoft.com/downloads/details.aspx?FamilyID=CE3FC537-86AE-4802-9A05-43E2A27A4B45&displaylang=en

Virtual Server COM interfaceVirtual Server 2005 R2 exposes a rich COM interface that contains 42 interfaces and hundreds of calls

which permits the user to monitor and control the virtual machine environment. All of the web-based

user interfaces in Virtual Server 2005 R2 use this COM interface via a scripting language, which allows

easy customization of the virtual machines. The scripting model is based on COM; therefore users are

not tied to a specific scripting language. Developers can choose between Visual Basic, C#, Perl, and

many other modern development languages. Furthermore, scripts can be “triggered” by certain events

within Virtual Server 2005 R2. Customers benefit from greater ease of customization and automation by

using the Virtual Server 2005 R2 COM API.

The scripting API makes Virtual Server 2005 R2 a powerful platform for virtualization solutions.

The scripting API enables programmatic control over the configuration and administration of virtual machines.

It automates virtual machine deployment and operations. It enables customers to integrate virtual machines into their existing IT infrastructural operations for

reduced cost and enhanced manageability.

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Monitoring and Management

MOM Virtual Server Support packThe Microsoft® Virtual Server 2005 R2 Management Pack enables you to monitor physical computers running the Virtual Server service, and the virtual machines that the service hosts, in Microsoft® Operations Manager 2005 (MOM). This Management Pack expands the monitoring and reporting capabilities of the Microsoft® Virtual Server 2005 Management Pack. You can use the Management Pack to monitor servers running Microsoft® Virtual Server 2005 R2 or Virtual Server 2005.

For more information on MOM, see the MOM Management Pack Guide .

Key Features in the Virtual Server Management PackThe R2 release of the Virtual Server 2005 Management Pack contains the following new features.

Alerts about the power state of all virtual machines.

Diagram view.

Virtualization Candidates report.

Performance History report.

A separate notification group for Virtual Server Management Pack alerts.  

Identification of the host and guest operating system for a virtual machine.

Alerting when a virtual machine name does not match the computer name of the guest

operating system.  

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Service Provider Licensing

The Service Provider License Agreement (SPLA) enables service providers and ISVs with a hosted offering to license Microsoft products on a monthly basis to provide services and hosted applications to their end customers.

You can find more information on Service Provider Licensing, including the use rights document at: http://www.microsoft.com/serviceproviders/licensing/default.mspx

Licensing modelService provider licensing includes licensing options for all major editions of Microsoft Windows Server 2003. Microsoft Windows Server 2003 Datacenter Edition provides the best model for licensing virtual dedicated hosting scenarios, as it provides for unlimited Virtual Server Guest instances to be created and run without additional license costs being due for each guest environment.

Note: this is specific to Web Hosting specific scenarios as described in the use rights document.

By simply licensing the server’s processors with Windows Server Datacenter Edition, customers will be able to run Windows Server Standard Edition, Enterprise Edition, Datacenter Edition as the host operating system.

Example:

Scenario Required Licensing

Single proc host running Windows Server 2003 Standard Edition. Each host has 6 virtual guests running Windows Server Standard Edition

1 processor license of Windows DataCenter Edition

Dual proc host running Windows Server 2003 Standard Edition. Each host has 8 virtual guests running Windows Server Standard Edition

2 processor licenses of Windows DataCenter Edition

Quad proc host running Windows Server 2003 Enterprise Edition. Each host has 20 virtual guests running Windows Server Standard Edition

4 processor licenses of Windows DataCenter Edition

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Useful Links Virtual Server Release Notes

Virtual Server Clustering

Hosted Network Structure

Enterprise Memory Architecture

Using iSCSI with Virtual Server

Using SAN with Virtual Server

MOM Management Pack Guide

SPLA Use Rights document

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