Boot from SAN in WindowsWord文件下载.docx

1、 Windows Server 2008 and Microsoft Windows Server 2003. It describes the advantages and complexities of the technology, and a number of key SAN boot deployment scenarios. The information contained in this document represents the current view of Microsoft Corporation on the issues discussed as of the

2、 date of publication. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information presented after the date of publication.This document is for informational purp

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6、ation. All rights reserved.Microsoft, Windows, Windows Server and WindowsVista are either registered trademarks or trademarks of Microsoft Corporation in the United States and/or other countries.The names of actual companies and products mentioned herein may be the trademarks of their respective own

7、ers.ContentsIntroduction 3Key Benefits of Boot from SAN 4The Boot Process: An Overview 5Local Boot 5Boot from SAN 5FC SAN Boot - Concepts and Configurations 6Single path Configuration 6Multipath Configuration 7Crash Dump File Creation 8Cluster Configuration 9Setup Boot from SAN 10Key Requirements 10

8、Basic Setup 10Migration to Windows 2008 and Windows 2008 R2 16Best Practices 17Paging Disk 17Redundancy Avoid Single Point of Failure 17Distributed Load 18Fabric Zoning 18Troubleshooting Boot from FC SAN 19Current Limitations to Windows Boot from SAN 21Additional Resources 22Summary 23IntroductionTo

9、days data centers have large scale server deployments and an ever increasing challenge for IT administrators to effectively manage and control costs. One key way is to reduce the hardware footprint by replacing large servers with highly compact rack-mountable forms. The densest of these forms is the

10、 blade server, which uses resources （such as device interfaces and power supplies） that are shared among the blade servers in an enclosure. In addition to reducing the hardware, electrical and square footage costs, blade servers are hot pluggable and use simplified cable configurations. Blade server

11、s are also easier to manage since a single server can manage all of the other servers in the same enclosure. While some blade servers have internal disks, they tend to have lower performance and capacity than SCSI disks. This is helping drive adoption of diskless blade servers that are used in combi

12、nation with networked storage.Boot from SAN leads to greater OPEX savings by providing better options for administrating and maintaining datacenter deployments. Nevertheless, it leads to increased CAPEX savings by moving towards storage consolidation in a SAN rather having a lot of local server stor

13、age.Key Benefits of Boot from SAN Boot from SAN helps enable all of the “RAS” advantages of fabric connectivity Redundancy, Availability, Serviceability. The key benefits are:Reduce Server Footprints Boot from SAN alleviates the necessity for each server to have its own direct-attached disk, elimina

14、ting internal disks as a potential point of failure. Thin diskless servers also take up less facility space, require less power, and are generally less expensive because they have fewer hardware components. Centralized Image ManagementWhen operating system images are stored on networked disks, all u

15、pgrades and fixes can be managed at a centralized location. Changes made to disks in a storage array are readily accessible by each server. Disaster and Server Failure RecoveryAll the boot information and production data stored on a local SAN can be replicated to a SAN at a remote disaster recovery

16、site. If a disaster destroys functionality of the servers at the primary site, the remote site can take over with minimal downtime. Recovery from server failures is simplified in a SAN environment. With the help of snapshots, mirrors of a failed server can be recovered quickly by booting from the or

17、iginal copy of its image. As a result, boot from SAN can greatly reduce the time required for server recovery.High AvailabilityA typical data center is highly redundant in nature - redundant paths, redundant disks and redundant storage controllers. When operating system images are stored on disks in

18、 the SAN, it supports high availability and eliminates the potential for mechanical failure of a local disk. Rapid RedeploymentBusinesses that experience temporary high production workloads can take advantage of SAN technologies to clone the boot image and distribute the image to multiple servers fo

19、r rapid deployment. Such servers may only need to be in production for hours or days and can be readily removed when the production need has been met. Highly efficient deployment of boot images makes temporary server usage a cost effective endeavor.GreenWhen boot images are stored on a SAN, it enabl

20、es the server not to have any local spinning media. Boot from SAN can provide greater power efficiency and help largely towards datacenter green initiatives. An Overview The boot process （previously known as booting or bootstrapping） is the iterative loading of the installed operating system code fr

21、om the boot device into computer memory after the computer is powered on. The BIOS （Basic Input / Output System） is the most basic code and is loaded first from the system firmware after POST initialization process. It initializes the computer hardware and reads in code that loads the operating syst

22、em, completes hardware setup and produces a fully functional operating system residing in memory. See the Appendix for a more detailed description of the boot process. The boot process can occur from a direct attached disk, over a local area network, or from networked storage. In all cases, a critic

23、al step to a successful boot is locating the boot disk. The device controlling that process depends on the boot type. Local BootThe most common booting approach is to boot from a direct-attached disk. The server BIOS locates the SCSI adapter BIOS, which contains the instructions that allow the serve

24、r to determine which of the internal disks is the boot device.Boot from SANBooting from SAN provides number of advantages Reduce OS image foot prints Enable centralized image management Enable rapid deployment scenarios Provide seamless disaster recovery optionsAll of the above key benefits of SAN a

25、re discussed in the following section of this white paper.With boot from SAN, the boot disk resides on the storage area network （SAN）, not locally on the server. The server communicates with the SAN through a host bus adapter （HBA）. The HBAs BIOS contain the instructions that enable the server to fi

26、nd the boot disk.Boot from SAN offers the advantages of reduced equipment costs. It also provides a number of other advantages, including reduced server maintenance, improved security and better performance. These factors are addressed in detail in the next section.FC SAN Boot - Concepts and Configu

27、rationsIT administrators can enable servers to boot from SAN by configuring the server and the underlying hardware components. After power on self test （POST）, the server hardware component fetches the boot block from the device that is designated as the boot device in the hardware BOIS settings. On

28、ce the hardware detects the boot device, it follows the regular boot process as explained in the Appendix.The order in which drivers are loaded is different for local boot and SAN boot. For FC SAN boot with Multi-Path I/O （MPIO）, the Device Specific Module （DSM） driver gets loaded very early in the

29、boot process so it can help manage the paths to the storage devices.Single path Configuration The simplest SAN configuration is shown in Figure1, two diskless servers, each with a single HBA connected to Fiber Channel storage. This configuration does not employ redundant components, which is a requi

30、rement for high availability servers. For boot from SAN with Windows, each server must have sole access to its own dedicated boot device. Figure1. Basic boot from SAN ConfigurationMultipath ConfigurationThe configuration shown in Figure 2 provides high availability and high performance with the addition of redundant HBAs, cabling, switches, and array controller ports. 2. Fully Redundant Boot from SAN ConfigurationCrash Dump File CreationIn the event of a system or kernel software component failure, a crash dump file is created to