User manual REDHAT ENTERPRISE LINUX 5 DM MULTIPATH CONFIGURATION

[. . . ] Red Hat Enterprise Linux 5 DM Multipath DM Multipath Configuration and Administration DM Multipath Red Hat Enterprise Linux 5 DM Multipath DM Multipath Configuration and Administration Edition 3 Copyright © 2009 Red Hat, Inc. This material may only be distributed subject to the terms and conditions set forth in the Open Publication License, V1. 0 or later (the latest version of the OPL is presently available at http://www. opencontent. org/openpub/). Red Hat and the Red Hat "Shadow Man" logo are registered trademarks of Red Hat, Inc. in the United States and other countries. [. . . ] Although you could blacklist the sda device using a devnode type, that would not be safe procedure since /dev/sda is not guaranteed to be the same on reboot. To blacklist individual devices, you can blacklist using the WWID of that device. Note that in the output to the multipath -v2 command, the WWID of the /dev/sda device is SIBM-ESXSST336732LC____F3ET0EP0Q000072428BX1. To blacklist this device, include the following in the /etc/multipath. conf file. blacklist { wwid SIBM-ESXSST336732LC____F3ET0EP0Q000072428BX1 } 3. After you have updated the /etc/multipath. conf file, you must manually tell the multipathd daemon to reload the file. The following command reloads the updated /etc/ multipath. conf file. service multipathd reload 4. Run the following commands: multipath -F multipath -v2 The local disk or disks should no longer be listed in the new multipath maps, as shown in the following example. [root@rh4cluster1 ~]# multipath -F 9 Chapter 3. Setting Up DM-Multipath [root@rh4cluster1 ~]# multipath -v2 create: 3600a0b80001327d80000006d43621677 [size=12 GB][features="0"][hwhandler="0"] \_ round-robin 0 \_ 2:0:0:0 sdb 8:16 \_ 3:0:0:0 sdf 8:80 create: 3600a0b80001327510000009a436215ec [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"][hwhandler="0"] \_ round-robin 0 \_ 2:0:0:2 sdd 8:48 \_ 3:0:0:2 sdh 8:112 create: 3600a0b80001327510000009b4362163e [size=12 GB][features="0"][hwhandler="0"] \_ round-robin 0 \_ 2:0:0:3 sde 8:64 \_ 3:0:0:3 sdi 8:128 3. 3. Adding Devices to the Multipathing Database By default, DM-Multipath includes support for the most common storage arrays that support DMMultipath. The default configuration values, including supported devices, can be found in the multipath. conf. defaults file. If you need to add a storage device that is not supported by default as a known multipath device, edit the /etc/multipath. conf file and insert the appropriate device information. For example, to add information about the HP Open-V series the entry looks like this: devices { device { vendor "HP" product "OPEN-V. " getuid_callout "/sbin/scsi_id -g -u -p0x80 -s /block/%n" } } For more information on the devices section of the configuration file, see Section 4. 5, "Configuration File Devices". 10 Chapter 4. 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 DMMultipath. The default configuration values and the supported devices can be found in the /usr/ share/doc/device-mapper-multipath-0. 4. 7/multipath. conf. defaults file. You can override the default configuration values for DM-Multipath by editing the /etc/ multipath. conf configuration file. If necessary, you can also add a storage array that is not supported by default to the configuration file. This chapter provides information on parsing and modifying the multipath. conf file. It contains sections on the following topics: · Configuration file overview · Configuration file blacklist · Configuration file defaults · Configuration file multipaths · Configuration file devices In the multipath configuration file, you need to specify only the sections that you need for your configuration, or that you wish to change from the default values specified in the multipath. conf. defaults file. If there are sections of the file that are not relevant to your environment or for which you do not need to override the default values, you can leave them commented out, as they are in the initial file. The configuration file allows regular expression description syntax. An annotated version of the configuration file can be found in /usr/share/doc/device-mappermultipathd-0. 4. 7/multipath. conf. annotated. 4. 1. Configuration File Overview The multipath configuration file is divided into the following sections: blacklist Listing of specific devices that will not be considered for multipath. [. . . ] DM-Multipath Administration and Troubleshooting the device mapper. The -ll option displays the information the -l displays in addition to all other available components of the system. When displaying the multipath configuration, there are three verbosity levels you can specify with the -v option of the multipath command. Specifying -v1 outputs the created or updated multipath names only, which you can then feed to other tools such as kpartx. [. . . ]