Windows Server High Availability with Microsoft MPIO

www.Microsoft.com/MPIO

Microsoft Corporation Published: January 2009

Abstract

A growing number of organizations require that their data be available 24x7, year round. To meet this requirement, centralized storage must be readily available and immune to outages at all times .The Microsoft Multipath I/O (MPIO) framework provides support for multiple data paths to storage to improve fault tolerance of connection to storage, and may in some cases provide greater aggregate throughput by using multiple paths at the same time.

This whitepaper is intended for the following groups:

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The IT executive who is responsible for ensuring data is highly reliable and available and makes the relevant procurement and evaluation decisions. The first half of this paper focuses upon the executive, providing an overview of the problem and the Microsoft implemented solution. ?

The storage administrator who is ultimately responsible for ensuring that an organization’s data remains highly available. The second half of the paper addresses the needs of the storage administrator and includes a trouble shooting section ?

Storage vendors who target Multi-Path solutions using the Microsoft MPIO framework in Windows Sever 2008 and Windows Server 2003 family of operating systems. .

Microsoft? Windows? Server 2008 White Paper

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Contents

High Availability Solutions.............................................................................................................3 Application Availability through Failover Clustering .........................................................................3 Storage Redundancy through RAID ...............................................................................................3 Storage Availability through MPIO .................................................................................................3 MPIO Solutions ..............................................................................................................................5

Multipath solutions in Windows Server 2008 ...............................................................................5 Making MPIO-Based Solutions Work .............................................................................................7 Device Discovery and Enumeration ...............................................................................................7 Unique Storage Device Identifier ...................................................................................................8 Dynamic Load Balancing ..............................................................................................................8 Error Handling, Failover and Recovery...........................................................................................8 Differences in load balancing terminology: ..................................................................................8 Differences in failover technology: ..............................................................................................9 The Windows Storage Stack and Drivers.....................................................................................11 Storage Stack and Device Drivers ...............................................................................................11 DSM Management ..................................................................................................................13 MPIO Drivers in Windows Server 2008 ........................................................................................13 MPIO DSM.................................................................................................................................13 Device Initialization .................................................................................................................14 MPIO device discovery ...............................................................................................................14 Request Handling ...................................................................................................................15 Error Handling ........................................................................................................................16 Details of the Windows Server 2008 Microsoft DSM ..................................................................16 Using MPIO on Windows Server 2008..........................................................................................18 Adding MPIO Support on Windows Server 2008...........................................................................18 MPIO Configuration and DSM installation.....................................................................................21 How to configure the Load Balance policy for a LUN: ....................................................................26 Troubleshooting Examples: .........................................................................................................29 Verify whether the storage is correctly setup with MPIO.............................................................29

Highly Available Storage: Multipath Solutions in Windows Server 2008 and Windows Server 2003

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Using mpclaim.exe to configure MPIO on Windows Server 2008.................................................31

Add MPIO support for FC device(s): .........................................................................................31 Add MPIO support for iSCSI devices: .......................................................................................32 Add MPIO support for all devices that are multipathed: ..............................................................32 Remove MPIO support for FC device(s): ..................................................................................32 Remove MPIO support for iSCSI devices:.................................................................................32 Remove MPIO support for all devices on the system: ................................................................32 Installation of MPIO on Server Core installations of Windows Server 2008 ................................34

To install MPIO on server core: ................................................................................................35 To remove the MPIO feature on server core: ............................................................................35 Access the MPIO control panel on server core: .........................................................................35 Appendix A – Script Example : Query the MPIO Policy for a device ............................................36 Appendix B – MPIO & DSM Configuration and best practices .....................................................38

To search for hardware ID’s registered with more than one DSM: ..............................................39 To add a hardware ID to be used with MPIO: ............................................................................40 Appendix C – Determining the Hardware ID to be used with MPIO ..............................................42 Appendix D – Enabling software tracing for MPIO .......................................................................45 Appendix E - MPIO timers ............................................................................................................47 Appendix F – Acronyms: .............................................................................................................48 Conclusion ..................................................................................................................................49 Resources....................................................................................................................................50

Highly Available Storage: Multipath Solutions in Windows Server 2008 and Windows Server 2003

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