REDHAT CLUSTER SUITE 4.7 DM MULTIPATH Configuration

Download or browse on-line these Configuration for Red Hat CLUSTER SUITE 4.7 DM MULTIPATH Other.

Red Hat CLUSTER SUITE 4.7 DM MULTIPATH Manual Information:

This manual for Red Hat CLUSTER SUITE 4.7 DM MULTIPATH, given in the PDF format, is available for free online viewing and download without logging on. The guide contains 38 pages, and the size of the file at download is 0.39 Mb. The document type is Configuration.

Download Manual

Summary of Contents:

[Page 1] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Red Hat Cluster Suite 4.7 DM Multipath DM Multipath Configuration and Administration ...

[Page 2] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

DM Multipath Red Hat Cluster Suite 4.7 DM Multipath DM Multipath Configuration and Administration Edition 1.0 Copyright © 2008 Red Hat, Inc. This material may only be distributed subject to the terms and conditions set forth in the Open Publication ...

[Page 3] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

iii Preface v 1. Audience ........................................................................................

[Page 4] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

iv ...

[Page 5] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

v 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 famil...

[Page 6] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Preface vi 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 m...

[Page 7] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Typographic Conventions vii The first sentence highlights the particular key cap to press. The second highlights two sets of three key caps, each set pressed simultaneously. If source code is discussed, class names, methods, functions, variable names...

[Page 8] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Preface viii Aside from standard usage for presenting the title of a work, italics denotes the first use of a new and important term. For example: When the Apache HTTP Server accepts requests, it dispatches child processes or threads to handle them. ...

[Page 9] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Notes and Warnings ix Note A note is a tip or shortcut or alternative approach to the task at hand. Ignoring a note should have no negative consequences, but you might miss out on a trick that makes your life easier. Important Important boxes detail ...

[Page 10] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

x ...

[Page 11] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Chapter 1. 1 Device Mapper Multipathing Device Mapper Multipathing (DM-Multipath) allows you to configure multiple I/O paths between server nodes and storage arrays into a single device. These I/O paths are physical SAN connections that can include s...

[Page 12] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Chapter 1. Device Mapper Multipathing 2 • HBA failure • FC cable failure • SAN switch failure • Array controller port failure With DM-Multipath configured, a failure at any of these points will cause DM-Multipath to switch to the alternate I/...

[Page 13] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Storage Array Support 3 In this configuration, I/O can be spread among those four paths. Figure 1.3. Active/Active Multipath Configuration with One RAID Device 1.2. Storage Array Support By default, DM-Multipath includes support for the most common s...

[Page 14] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Chapter 1. Device Mapper Multipathing 4 Component Description kpartx command Creates device mapper devices for the partitions on a device It is necessary to use this command for DOS-based partitions with DM- MP. The kpartx is provided in its own pack...

[Page 15] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Chapter 2. 5 Multipath Devices Without DM-Multipath, each path from a server node to a storage controller is treated by the system as a separate device, even when the I/O path connects the same server node to the same storage controller. DM-Multipath...

[Page 16] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Chapter 2. Multipath Devices 6 a cluster. For information on the multipaths section of the multipath configuration file, see see Section 4.4, “Multipaths Device Configuration Attributes”. • If you want the system-defined user-friendly names to ...

[Page 17] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Chapter 3. 7 Setting Up DM-Multipath This chapter provides step-by-step example procedures for configuring DM-Multipath. It includes the following procedures: • Basic DM-Multipath setup • Ignoring local disks • Adding more devices to the config...

[Page 18] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Chapter 3. Setting Up DM-Multipath 8 multipath -v2 The multipath -v2 command prints out multipathed paths that show which devices are multipathed. If the command does not print anything out, ensure that all SAN connections are set up properly and the...

[Page 19] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Ignoring Local Disks when Generating Multipath Devices 9 \_ round-robin 0 \_ 2:0:0:1 sdc 8:32 \_ 3:0:0:1 sdg 8:96 create: 3600a0b80001327d800000070436216b3 [size=12 GB][features="0"][hwhandler="0"] \_ round-robin 0 ...

[Page 20] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Chapter 3. Setting Up DM-Multipath 10 [size=12 GB][features="0"][hwhandler="0"] \_ round-robin 0 \_ 2:0:0:1 sdc 8:32 \_ 3:0:0:1 sdg 8:96 create: 3600a0b80001327d800000070436216b3 [size=12 GB][features="0"]...

[Page 21] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Chapter 4. 11 The DM-Multipath Configuration File By default, DM-Multipath provides configuration values for the most common uses of multipathing. In addition, DM-Multipath includes support for the most common storage arrays that support DM- Multipat...

[Page 22] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Chapter 4. The DM-Multipath Configuration File 12 When the system determines the attributes of a multipath device, first it checks the multipath settings, then the per devices settings, then the multipath system defaults. 4.2. Configuration File Blac...

[Page 23] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Configuration File Defaults 13 devnode_blacklist { devnode "^sd[a-z]" } You can use a devnode entry in the blacklist section of the configuraion file to specify individual devices to blacklist rather than all devices of specific type...

[Page 24] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Chapter 4. The DM-Multipath Configuration File 14 To overwrite the default value for any of the configuration parameters, you can copy the relevant line from this template into the defaults section and uncomment it. For example, to overwrite the path...

[Page 25] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Multipaths Device Configuration Attributes 15 Attribute Description rr_min_io Specifies the number of I/O requests to route to a path before switching to the next path in the current path group. The default value is 1000. rr_weight If set to prioriti...

[Page 26] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Chapter 4. The DM-Multipath Configuration File 16 Attribute Description wwid Specifies the WWID of the multipath device to which the multipath attributes apply. alias Specifies the symbolic name for the multipath device to which the multipath attribu...

[Page 27] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Configuration File Devices 17 multipaths { multipath { wwid 3600508b4000156d70001200000b0000 alias yellow path_grouping_policy multibus path_checker ...

[Page 28] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Chapter 4. The DM-Multipath Configuration File 18 If the device is active/passive, but it automatically switches paths with I/O to the passive path, you need to change the checker function to one that does not send IO/ to the path to test if it is wo...

[Page 29] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Configuration File Devices 19 Attribute Description hardware_handler Specifies a module that will be used to perform hardware specific actions when switching path groups or handling I/O errors. Possible values include 0, 1 emc, and 1 rdac. The defaul...

[Page 30] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

20 ...

[Page 31] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Chapter 5. 21 DM-Multipath Administration and Troubleshooting This chapter will provide information on administering DM-Multipath on a running system. It includes sections on the following topics: • Multipath Command Output • Multipath Queries wi...

[Page 32] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Chapter 5. DM-Multipath Administration and Troubleshooting 22 If the path is up and ready for I/O, the status of the path is ready or active. If the path is down, the status is faulty or failed. The path status is updated periodically by the multipat...

[Page 33] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Determining Device Mapper Entries with the dmsetup Command 23 Option Description -F Remove all multipath devices. Table 5.1. Useful multipath Command Options 5.4. Determining Device Mapper Entries with the dmsetup Command You can use the dmsetup comm...

[Page 34] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Chapter 5. DM-Multipath Administration and Troubleshooting 24 The following command sequence ensures that multipath has picked up any changes to the multipath.conf, # multipathd -k > > reconfigure > > CTRL-D Use the following command sequ...

[Page 35] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

25 Appendix A. Revision History Revision History Revision 1.0 ...

[Page 36] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

26 ...

[Page 37] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

27 Index A active/active configuration definition, 1 illustration, 2 active/passive configuration definition, 1 illustration, 1 alias parameter , 16 configuration file, 5 B bindings_file parameter, 14 bl_product parameter, 18 blacklist configuration ...

[Page 38] Red Hat CLUSTER SUITE 4.7 DM MULTIPATH

Index 28 L local disks, ignoring, 8 LVM physical volumes multipath devices, 6 lvm.conf file , 6 M modprobe command, 7 multipath command , 3, 7 options, 22 output, 21 queries, 22 multipath devices, 5 logical volumes, 6 LVM physical volumes, 6 multipat...