Storage Array Support; Dm-Multipath Components - Red Hat ENTERPRISE LINUX 5 DM MULTIPATH Configuration And Administration Manual

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 storage arrays that support DM-
Multipath. The supported devices can be found in the multipath.conf.defaults file. If your
storage array supports DM-Multipath and is not configured by default in this file, you may need to add
them to the DM-Multipath configuration file, multipath.conf. For information on the DM-Multipath
Chapter 4, The DM-Multipath Configuration
configuration file, see
Some storage arrays require special handling of I/O errors and path switching. These require separate
hardware handler kernel modules.

1.3. DM-Multipath Components

Table 1.1, "DM-Multipath
Component
dm-multipath kernel module
multipath command
multipathd daemon
Components". describes the components of DM-Multipath.
Description
Reroutes I/O and supports failover for paths and path groups.
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.
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/
multipath.conf file.
Storage Array Support
File.
3