Red Hat GNBD WITH GLOBAL FILE SYSTEM IN RHEL 4.5 Guia de Instalação descarregar pdf (Página 12)

Chapter 1. Device Mapper Multipathing

Figure 1.3. Active/Active Multipath Configuration with One RAID Device

1.3. 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

configuration file, see Chapter 4, The DM-Multipath Configuration File.

Some storage arrays require special handling of I/O errors and path switching. These require separate

hardware handler kernel modules.

1.4. DM-Multipath Components

Table 1.1, “DM-Multipath Components”. describes the components of DM-Multipath.

Table 1.1. DM-Multipath Components

Component Description

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

multipath 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.

multipathd 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/

multipath.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-mapper-multipath package depends on it.

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