Installation guide

Table 1.1. DM-Multipath Component s

Component Description

dm -multipath kernel module Reroutes I/O and supports failover for paths and path groups.

m ultipath command Lists and configures multipath devices. Normally started up with

/etc/rc.sysinit, it can also be started up by a udev program

whenever a block device is added or it can be run by the

initramfs file system.

m ultipathd daemon Monitors paths; as paths fail and come back, it may initiate path

group switches. Provides for interactive changes to multipath

devices. This must be restarted for any changes to the

/etc/m ultipath.conf file.

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 package, but the device-

m apper-m ultipath package depends on it.

1.4. DM-Multipath Setup Overview

DM-Multipath includes compiled-in default settings that are suitable for common multipath configurations.

Setting up DM-multipath is often a simple procedure.

The basic procedure for configuring your system with DM-Multipath is as follows:

1. Install device-m apper-m ultipath rpm.

2. Edit the m ultipath.conf configuration file:

comment out the default blacklist

change any of the existing defaults as needed

save the configuration file

3. Start the multipath daemons.

4. Create the multipath device with the m ultipath command.

Detailed setup instructions for several example multipath configurations are provided in see Chapter 3,

Setting Up DM-Multipath.

Chapter 1. Device Mapper Multipathing