5. Hypervisor Architecture Host OS VMM Guest 1 Guest 2 VMM Guest 1 Guest 2 Host OS VMM Guest 1 Guest 2 Type-2 VMM Type-1 VMM Hybrid VMM Examples: JVM CLR Examples: Virtual PC and Virtual Server 2005 R2 Examples: Windows Server Virtualization Hardware Hardware Hardware Hypervisor Architecture
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7. Benefits of Server Virtualization Simplified support of older operating systems Reduced hardware costs through more efficient use of hardware Benefits of server virtualization : Reduced management costs through less hardware Simplified maintenance and failure recovery
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14. Windows Server Virtualization Architecture Parent Partition Child Partitions Virtualization Stack VM Service WMI Provider Virtualization Service Providers (VSPs) Server Core Applications Windows Kernel Virtualization Service Clients (VSCs) IHV Drivers Enlightenments Windows Hypervisor “ Designed for Windows” Server Hardware User Mode Windows Kernel Kernel Mode VM Worker Processes Provided by: Windows ISV OEM Windows Virtualization VM Bus
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16. Hardware Considerations for Virtualization Physical memory must be enough to support all virtual machines at the same time Processor capacity must be enough to support all virtual machines at the same time Hardware considerations : Disk I/O is intensive for .vhd files and memory contents stored on disk Multiple VMs share the network capacity of the hardware
17. Software Considerations for Server Virtualization The guest operating system must be supported Windows Server virtualization can run operating systems without modification Software considerations : Hypervisor aware operating system can make more efficient use of hardware resources
18. Management Considerations for Server Virtualization An MMC snap-in is used for management Physical hardware problems will affect multiple VMs Management considerations : Parent partition failure affects child partitions Virtual machines can be more difficult to monitor Monitor with System Center Operations Manager 2007
Module 15: Server Virtualization Overview Course 6420A Presentation: 30 minutes This module helps students to the fundamental functions included with Windows Server Virtualization. Required materials To teach this module, you need the Microsoft ® Office PowerPoint® file 6420A_15.ppt. Important: It is recommended that you use PowerPoint 2002 or a later version to display the slides for this course. If you use PowerPoint Viewer or an earlier version of PowerPoint, all the features of the slides might not be displayed correctly. Preparation tasks To prepare for this module: Read all of the materials for this module. Practice performing the demonstrations and the lab exercises. Work through the Module Review and Takeaways section and determine how you will use this section to reinforce student learning and promote knowledge transfer to on-the-job performance. Make sure that students are aware that there are additional information and resources for the module on the Course Companion CD.
Module 15: Server Virtualization Overview Course 6420A
Module 15: Server Virtualization Overview Course 6420A
Module 15: Server Virtualization Overview Course 6420A Throughout this course, students are using Virtual Server and virtual machines. This is one way that server virtualization can be implemented using a hypervisor. The next slides show various ways that hypervisors can be used. Question: How does server virtualization relate to a multi-boot configuration? Answer: A multi-boot configuration allows a multiple operating systems to be installed on a single computer, but only one operating system is running at a time. For example, if Linux and Microsoft Windows® operating systems are installed on a multi-boot system, then either Windows or Linux can be running, but not both at the same time. Server virtualization allows multiple operating systems to run at the same time on a single computer.
Module 15: Server Virtualization Overview Course 6420A Explain the various implementations of virtualization: Type 2 - Used by Java or Common Language Runtime (CLR) to isolate application instances. Hybrid - Used for server virtualization to run multiple operating systems. Type 1 – Use for server virtualization to run multiple operating systems. In most cases, only type 1 is referred to as a hypervisor. The hypervisor isolates guests from the hardware and each other. Question: Why will a type 1 architecture have better performance than a type 2 architecture? Answer: A type 1 architecture requires the guests to run within the host operating system, which creates additional overhead. A type 2 architecture reduces overhead by running the hypervisor before any operating systems.
Module 15: Server Virtualization Overview Course 6420A The key benefits of a microkernelized architecture are as follows: Eliminates driver restrictions because hardware is not being emulated Simplifies hypervisor development because there is less code without drivers Increases security because third-party code is not used for hardware emulation Increases performance because hypervisor is performing less work Ensure that students understand that the guests still rely on the parent virtual machine (VM) for access to hardware. Question: With a microkernelized hypervisor, will additional software need to be installed for a Guest operating system to run in a VM? Answer: Yes, the hypervisor does not emulate hardware. So, you need to install the driver software in the guest operating systems.
Module 15: Server Virtualization Overview Course 6420A Describe the problems that server virtualization resolves: Difficult to find hardware drivers for older operating systems Servers that have very low utilization of hardware Maintenance of many physical servers Recovery of VMs and migration to new hardware Question: Which hardware components in a server may have low utilization? Answer: CPU utilization in many servers is low. Disk utilization may also be low, depending on the application it is being used for. Memory is the resource most likely to be a bottleneck when implementing virtualization.
Module 15: Server Virtualization Overview Course 6420A Explain how each of the server virtualization scenarios is useful: • Server consolidation – reduce hardware costs and hardware management costs • Testing and development – reduce the amount of hardware dedicated to testing and create multiple server testing scenarios • Re-host legacy applications – avoid the need to find hardware drivers for legacy operating systems • Disaster recovery – easily move a virtual machine to another physical server when the physical server experiences a problem. Question: What are some types of testing that can be performed with a virtual environment? Answer: Any software testing that does not rely on specific hardware can be performed in a virtual environment. For example, you can test application patches. However, you cannot test hardware-specific software, such as drivers, because the hardware is not present in the VM.
Module 15: Server Virtualization Overview Course 6420A
Module 15: Server Virtualization Overview Course 6420A Students are using Virtual Server to manage the virtual machines in this course. Explain the role of .vhd and vmc files. This will help students understand how a virtual machine can be relocated from one server to another. If students are interested, you can also mention: • Undo disks • Differencing disks • Memory state saved to disk Question: What benefit is there to a fixed-size virtual disk rather than growing dynamically? Answer: A fixed-size virtual disk will have better performance than a dynamically expanding disk. Each time a dynamically expanding virtual disk expands, there is a performance loss as the vhd file is expanded on the disk. Also, because a dynamically expanding disk is created over time, the vhd file is more likely to be fragmented on the physical disk, which will cause slower disk performance.
Module 15: Server Virtualization Overview Course 6420A Describe the features of Windows Server Virtualization and why they are a benefit: • A bare metal hypervisor for 64-bit editions of Windows Server® 2008 – more secure and faster • Supports dynamic resource allocation – add process and memory to VMs without restarts • Supports 32-bit and 64-bit guests – Can be used to support new or older operating systems • Live migration of virtual machines – Allows for maintenance of physical servers without downtime and enhances disaster recovery. Question: What is the benefit of dynamic resource allocation between child partitions? Answer: This allows you to allocate more resources to a child partition when it is low on resources. For example, you can increase the processor or memory allocation without restarting the virtual machine.
Module 15: Server Virtualization Overview Course 6420A Key things to note about the hardware and software requirements: The Windows Web Server 2008 operating system does not include virtualization Only 64-bit editions of Windows Server 2008 support virtualization, but guests can be 32-bit or 64-bit The required processor features are commonly available in current server processors Question: Why are hardware-assisted virtualization and hardware-enabled DEP required by Windows Server Virtualization? Answer: These features increase the performance of Windows Server Virtualization by offloading tasks onto hardware. To ensure adequate performance and simplify development, they are required.
Module 15: Server Virtualization Overview Course 6420A Question: Why are snapshots useful for system updates? Answer: A snapshot allows you to take a system backup with no downtime. And because it takes a copy of the entire system, you don’t need to worry about the integrity of transactions that are being processed. However, you should be aware that if an application uses multiple servers, backing up a single server may not be enough to ensure application integrity. For example, an application that uses a database server and an application server may also update the database structure when the application server is updated.
Module 15: Server Virtualization Overview Course 6420A The main goal of this topic is to understand how a child partition relates to the parent partition. Windows Server Virtualization still uses virtualized hardware in the child partitions, but this hardware is synthetic rather than emulated. Virtualization Service Clients are additional software installed in the child partition operating system to provide synthetic hardware. VMBus is a communication path between the parent partition and the child. Enlightenments are capabilities of the operating system to recognize it is running in a virtualized environment. In particular, Windows Server 2008 optimizes memory management differently when virtualized. Independent hardware vendor (IHV) drivers are the drivers that communicate with physical hardware on the server. Hardware communication process: App > VSC > VMBus > VSP > Driver > Hardware (through hypervisor) Virtualization stack is the monitoring and management of child partitions. Other scenarios: XEN virtualization for Linux – additional software is installed in the child to support XEN virtualization; still uses VMBus Non-aware operating system – additional software is installed to provide device emulation; VMBus is not used Question: From the perspective of the user, how do synthetic hardware devices vary from emulated hardware devices? Answer: From a user perspective, there is no difference. In both cases, drivers are installed to support the hardware devices. Both types of hardware devices appear in device manager. The VMBus appears in device manger as well.
Module 15: Server Virtualization Overview Course 6420A
Module 15: Server Virtualization Overview Course 6420A Describe the hardware consideration for students. Discuss how the specifications change as more virtual machines are added. Question: How can you expand disk throughput? Answer: You can expand disk throughput by adding additional disks and using redundant array of independent drives (RAID). RAID 10 (striped set of mirrored disks) is the most effective for increasing disk throughput. If disk throughput requirements are very high, a storage area network (SAN) may be used. You may also use small computer system interface (SCSI) disks instead of serial advanced technology attachment (SATA).
Module 15: Server Virtualization Overview Course 6420A Describe why a guest operating system must be supported. In addition, differentiate between an operating system that is hypervisor aware and one that is not. Hypervisor aware Non-hypervisor aware Talk to hardware directly Use emulated hardware Windows Server 2008 Previous versions of Windows Question: Which Windows operating system will have the best performance when virtualized? Answer: Windows Server 2008 is the only Windows operating system that is hypervisor aware. Consequently, it will have the best performance because it will optimize for a virtualized environment.
Module 15: Server Virtualization Overview Course 6420A Discuss the risk of problems affecting multiple virtual machines. Mention that using server core as the parent partition reduces the risk of failure. Mention that some things are more difficult to monitor with virtual machines. For example, a standard network sniffer may not see network traffic between virtual machines because those packets are never transmitted on the network infrastructure. References: System Center Operations Manager 2007 Web page on the Microsoft Web site http://go.microsoft.com/fwlink/?LinkId=103919 Question: How does using Server Core make the parent partition more stable? Answer: Server Core has a minimal set of Windows features and no graphical interface. By reducing the available features, the risk of failure is minimized. This also increases security.
Module 15: Server Virtualization Overview Course 6420A Describe what system center virtual machine manager is and how it simplifies the management of VMs. This tool can manage VMs in Virtual Server and Windows Server Virtualization.
Module 15: Server Virtualization Overview Course 6420A Question: When a planned migration is performed using Quick Migration, do the applications on the VM need to be restarted? Answer: No, when a planned migration is performed, the current state of the VM is saved to disk. This includes all information in memory of the VM. The files on the SAN are then made available to the standby server for restoration. When the VM is restored, all applications that were running at the time the current state was saved are still running.
Module 15: Server Virtualization Overview Course 6420A Review Questions Point the students to the appropriate section in the course so that they are able to answer the questions presented in this section. Question: What is the difference between a monolithic and microkernelized hypervisor? Answer: In both cases, the hypervisor is responsible for partitioning system hardware for the host and guest operating systems. However, a monolithic hypervisor includes emulated hardware and drivers. A microkernelized hypervisor performs only partitioning duties and is much smaller. This makes a microkernelized hypervisor better performing and more secure. Question: What are the hardware requirements for running Windows Server Virtualization? Answer: Windows Server Virtualization requires a 64-bit x86 processor. The processor must also include hardware-assisted virtualization and hardware-enabled Data Execution Prevention. These features are available in both AMD and Intel processors. Question: What considerations beyond the basic hardware requirements must be considered when purchasing hardware to host VMs? Answer: The servers hosting VMs must have sufficient capacity to support all VMs running at the same time. There must be enough physical memory, processing capacity, disk throughput, and network throughput. The performance of VMs will be degraded if any component in the host server is overloaded. Real-world Issues and Scenarios You can either discuss possible solutions for the scenarios at the end of the module or assign these scenarios as homework for the students. If you assign the scenarios as homework, you should provide some high-level hints that might help the students solve the problem stated in the scenarios. You can also do a follow-up debriefing the following day on some of the scenarios that have been assigned as homework to students. Scenario: You are an IT architect at a large insurance provider with seven physical locations, 12,000 users and 220 servers. Your organization wants to use server virtualization to reduce management and hardware costs by combining existing servers on new hardware. What criteria will you use when you select servers for consolidation? Answer: One way to automate the process would be by using System Center Virtual Machine Manager. You would not want to virtualize servers that are very demanding on resources. Some criteria you can use include the following: Older hardware that may be failing Servers that have low resource utilization Servers where you want to improve failure recovery. Scenario: You are an IT architect at a large insurance provider. You have migrated many important applications to VMs and want to increase the availability of those VMs. How can availability of VMs be increased when you use Windows Server Virtualization? Answer: Quick Migration increases the availability of VMs by putting them in a failover cluster. When the node in the cluster hosting the VM fails, the VM is restarted on another node. For maintenance, planned migrations can be performed with significantly less downtime. Scenario: You are the manager responsible for controlling the process that is used for testing new application updates and releases at a large insurance provider. In the past, you have maintained development, test, and production servers for all applications. This resulted in hundreds of servers being stored in the datacenter. How can you use Windows Server Virtualization to reduce hardware costs for development and testing? Answer: Instead of having physical servers for development and testing, you can use virtual servers. The development and testing servers will have much lower utilization than the production servers and many can be run on a single, physical server. Frequently, the development and testing servers can be shut down when they are not in use to further increase scalability. You can use System Center Virtual Machine Manager to help manage the VMs, including delegation of VM creation to testing staff. Best Practices Help the students understand the best practices presented in this section. Ask students to consider these best practices in the context of their own business situations.
Module x: Title Course xxxxy Remind students to complete the course evaluation.
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