Red Hat DEVICE-MAPPER MULTIPATH 4.6 Manual de instrucciones

Using Device-Mapper Multipath

Configuration and

Administration

4.6

DM_Multipath

ISBN: N/A

Publication date: July 2008

This book provides information on using the Device-Mapper Multipath feature of Red Hat

Enterprise Linux 4.6

Using Device-Mapper Multipath

Using Device-Mapper Multipath: Configuration and

Administration

Open Publication License, V1.0 or later with the restrictions noted below (the latest version of the OPL is presently

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Distribution of substantively modified versions of this document is prohibited without the explicit permission of the

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Using Device-Mapper Multipath

Preface ....................................................................................................................vii

1. Audience ...................................................................................................... vii

2. Related Documentation ................................................................................. vii

3. Feedback .................................................................................................... viii

4. Document Conventions ................................................................................ viii

1. Device Mapper Multipathing .................................................................................... 1

1. Overview of DM-Multipath ............................................................................... 1

2. Storage Array Support .................................................................................... 4

3. DM-Multipath Components ............................................................................. 4

4. DM-Multipath Setup Overview ......................................................................... 5

2. Multipath Devices ................................................................................................... 7

1. Multipath Device Identifiers ............................................................................. 7

2. Consistent Multipath Device Names in a Cluster .............................................. 7

3. Multipath Device Attributes ............................................................................. 8

4. Multipath Devices in Logical Volumes .............................................................. 8

3. Setting Up DM-Multipath ........................................................................................11

1. Setting Up DM-Multipath ................................................................................11

2. Ignoring Local Disks when Generating Multipath Devices ................................12

3. Adding Devices to the Multipathing Database .................................................14

4. The DM-Multipath Configuration File ......................................................................15

1. Configuration File Overview ...........................................................................15

2. Configuration File Blacklist .............................................................................16

2.1. Blacklisting by WWID .........................................................................16

2.2. Blacklisting By Device Name ...............................................................17

3. Configuration File Defaults .............................................................................17

4. Multipaths Device Configuration Attributes ......................................................20

5. Configuration File Devices .............................................................................22

5. DM-Multipath Administration and Troubleshooting ...................................................27

1. Multipath Command Output ...........................................................................27

2. Multipath Queries with multipath Command ....................................................28

3. Multipath Command Options ..........................................................................28

4. Determining Device Mapper Entries with the dmsetup Command .....................29

5. Troubleshooting with the multipathd Interactive Console ..................................29

Index .......................................................................................................................31

Preface

This book describes the Device Mapper Multipath (DM-Multipath) feature of Red Hat Enterprise

Linux.

1. Audience

This book is intended to be used by system administrators managing systems running the Linux

operating system. It requires familiarity with Red Hat Enterprise Linux.

2. Related Documentation

For more information about using Red Hat Enterprise Linux, refer to the following resources:

•Red Hat Enterprise Linux Installation Guide — Provides information regarding installation of

Red Hat Enterprise Linux.

•Red Hat Enterprise Linux Introduction to System Administration — Provides introductory

information for new Red Hat Enterprise Linux system administrators.

•Red Hat Enterprise Linux System Administration Guide — Provides more detailed information

about configuring Red Hat Enterprise Linux to suit your particular needs as a user.

•Red Hat Enterprise Linux Reference Guide — Provides detailed information suited for more

experienced users to reference when needed, as opposed to step-by-step instructions.

•Red Hat Enterprise Linux Security Guide — Details the planning and the tools involved in

creating a secured computing environment for the data center, workplace, and home.

For more information about Red Hat Cluster Suite for Red Hat Enterprise Linux, refer to the

following resources:

•Red Hat Cluster Suite Overview — Provides a high level overview of the Red Hat Cluster

Suite.

•Configuring and Managing a Red Hat Cluster — Provides information about installing,

configuring and managing Red Hat Cluster components.

•Global File System: Configuration and Administration — Provides information about installing,

configuring, and maintaining Red Hat GFS (Red Hat Global File System).

•LVM Administrator's Guide: Configuration and Administration — Provides a description of the

Logical Volume Manager (LVM), including information on running LVM in a clustered

environment.

•Using GNBD with Global File System — Provides an overview on using Global Network Block

Device (GNBD) with Red Hat GFS.

vii

•Linux Virtual Server Administration — Provides information on configuring high-performance

systems and services with the Linux Virtual Server (LVS).

•Red Hat Cluster Suite Release Notes — Provides information about the current release of

Red Hat Cluster Suite.

Red Hat Cluster Suite documentation and other Red Hat documents are available in HTML and

PDF versions online at the following location:

http://www.redhat.com/docs

3. Feedback

If you spot a typo, or if you have thought of a way to make this manual better, we would love to

hear from you. Please submit a report in Bugzilla (http://bugzilla.redhat.com/bugzilla/) against

the component rh-cs.

Be sure to mention the manual's identifier:

rh-MPIO(EN)-4.6 (2008-07-31T15:20)

By mentioning this manual's identifier, we know exactly which version of the guide you have.

If you have a suggestion for improving the documentation, try to be as specific as possible. If

you have found an error, please include the section number and some of the surrounding text

so we can find it easily.

4. Document Conventions

Certain words in this manual are represented in different fonts, styles, and weights. This

highlighting indicates that the word is part of a specific category. The categories include the

following:

Courier font

Courier font represents commands,file names and paths, and prompts .

When shown as below, it indicates computer output:

Desktop about.html logs paulwesterberg.png

Mail backupfiles mail reports

bold Courier font

Bold Courier font represents text that you are to type, such as: service jonas start

Preface

viii

If you have to run a command as root, the root prompt (#) precedes the command:

#gconftool-2

italic Courier font

Italic Courier font represents a variable, such as an installation directory:

install_dir/bin/

bold font

Bold font represents application programs and text found on a graphical interface.

When shown like this: OK , it indicates a button on a graphical application interface.

Additionally, the manual uses different strategies to draw your attention to pieces of information.

In order of how critical the information is to you, these items are marked as follows:

Note

A note is typically information that you need to understand the behavior of the

system.

Tip

A tip is typically an alternative way of performing a task.

Important

Important information is necessary, but possibly unexpected, such as a

configuration change that will not persist after a reboot.

Caution

A caution indicates an act that would violate your support agreement, such as

recompiling the kernel.

Document Conventions

Warning

A warning indicates potential data loss, as may happen when tuning hardware

for maximum performance.

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