To provide a redundant path to the storage array, you can configure multipath software.

.Before you begin

You must install the required packages on your system.

  • For Red Hat (RHEL) hosts, verify the packages are installed by running rpm -q device-mapper-multipath.

  • For SLES hosts, verify the packages are installed by running rpm -q multipath-tools.

If you have not already installed the operating system, use the media supplied by your operating system vendor.

About this task

Multipath software provides a redundant path to the storage array in case one of the physical paths is disrupted. The multipath software presents the operating system with a single virtual device that represents the active physical paths to the storage. The multipath software also manages the failover process that updates the virtual device.

You use the device mapper multipath (DM-MP) tool for Linux installations. By default, DM-MP is disabled in RHEL and SLES. Complete the following steps to enable DM-MP components on the host.

  1. If a multipath.conf file is not already created, run the # touch /etc/multipath.conf command.

  2. Use the default multipath settings by leaving the multipath.conf file blank.

  3. Start the multipath service.

    # systemctl start multipathd
  4. Save your kernel version by running the uname -r command.

    # uname -r

    You will use this information when you assign volumes to the host.

  5. Enable the multipathd daemon on boot.

    systemctl enable multipathd
  6. Rebuild the initramfs image or the initrd image under /boot directory:

    dracut --force --add multipath
  7. Make sure that the newly created /boot/initrams- image or /boot/initrd- image is selected in the boot configuration file.

    For example, for grub it is /boot/grub/menu.lst and for grub2 it is /boot/grub2/menu.cfg.

  8. Use the Create host manually procedure in the online help to check whether the hosts are defined. Verify that each host type setting is based on the kernel information gathered in step 4.

Automatic Load Balancing is disabled for any volumes mapped to hosts running kernel 3.9 or earlier.
  1. Reboot the host.