Settings for a multipath boot disk environment

To install HDLM in a boot disk environment that uses a SCSI device, and set up the environment:

This subsection describes how to perform a new installation of HDLM in a single-path boot disk environment that uses a SCSI device and how to configure a multipath boot disk environment.

To manually configure an environment without using the utility for creating an HDLM boot disk environment (dlmbootstart), see MANUALLY_SETTING_A_BOOT_DISK_ENVIRONMENT=GUID-71081C28-A668-4BF2-8182-1D9455EB30FA=2=EN=.html.

Note that if the settings are incorrect, the OS might not start. For details about what action to take if the OS cannot be started from an HDLM device, see BOOT_PERFORMING_AN_UPGRADE_INSTALLATION_OF_HDLM=GUID-068BB27C-E7E0-41F4-8C4C-55E8865333AE=2=EN=.html.

1. Log in to Linux as a user with root permissions.

2. Install HDLM.

   See PERFORMING_A_NEW_INSTALLATION_OF_HDLM=GUID-B0AB134E-B3E9-4110-ACC0-9D650B07E889=3=EN=.html, and then create an HDLM device by performing step 2 to 12.

3. Execute the swapoff command to disable a swap device.

   An example of executing the command to disable all swap devices is as follows:

   # /sbin/swapoff -a

   In an environment where all of the following conditions are met, if you perform the step while a swap device is enabled, the host might take a while to stop.

   Make sure to disable the swap, and then perform the step.

   • Either of the following OSs is used:

     • Red Hat Enterprise Linux 7, 8, 9

     • Oracle Linux 7, 8, 9

     • SUSE LINUX Enterprise Server 12, 15

   • The HDLM management-target device is enabled as a swap device.

4. Execute the utility for creating an HDLM boot disk environment (dlmbootstart) to configure a boot disk environment that uses HDLM.

   For Red Hat Enterprise Linux 8 version 8.8 or later, before executing the utility for creating an HDLM boot disk environment (dlmbootstart), confirm that the multipath_component_detection line in the /etc/lvm/lvm.conf file is not 1, change it to 0. Comment out the multipath_component_detection line and add the following underlined part.

   Before editing:

   devices {
   :
   multipath_component_detection = 1
   :
   }

   After editing:

   devices {
   :
   # multipath_component_detection = 1
   multipath_component_detection = 0
   :
   }

   For Red Hat Enterprise Linux 7, Oracle Linux 7, or Oracle Unbreakable Enterprise Kernel 7, before executing the utility for creating an HDLM boot disk environment (dlmbootstart), confirm that the allow_changes_with_duplicate_pvs line in the /etc/lvm/lvm.conf file is not 0. If it is set to 0, change it to 1. Comment out the allow_changes_with_duplicate_pvs line and add the following underlined part.

   Before editing:

   devices {
   :
   allow_changes_with_duplicate_pvs = 0
   :
   }

   After editing:

   devices {
   :
   # allow_changes_with_duplicate_pvs = 0
   allow_changes_with_duplicate_pvs = 1
   :
   }

   # /opt/DynamicLinkManager/bin/dlmbootstart -set hdlm

   Note

   Do not turn off the power of the host machine during execution of the dlmbootstart utility. Also, do not turn off the power of the host machine after the dlmbootstart utility is forced to stop.

   Note that if you turn off the power to the host machine, the OS might be unable to start. If you cannot start the OS, contact your HDLM vendor or maintenance company, and report the information that was collected by the DLMgetras utility.

5. Shut down the host.

   Execute the following command to shut down the host:

   # shutdown -h now

6. Add a path to the LU (system disk) and then change the configuration from a single-path configuration to a multi-path configuration.

7. Start the host.

8. Check that the HDLM boot disk environment is configured.

   See /proc/mounts to check the devices mounted on the root (/). Then execute the following command to output the root information and check the devices that are output.

   # /bin/cat /proc/mounts | /bin/grep -w / | /bin/grep -v rootfs

   Check as follows, depending on the devices that are output.

   • If /dev/{HDLM-device} is output:

     The HDLM boot disk environment is used.

   • If another device is output:

   1. Execute the /usr/bin/readlink -f {output-device} command.

      The full path of the file is output.

   2. Execute the /bin/ls -l {output-device} command.

      In a general file, the major and minor values are displayed where the file size is displayed.

   3. Execute the following command with the major value specified for the argument:

      # /bin/cat /proc/devices | /bin/grep -w {major}

      • If sddlmfdrv is output, the HDLM boot disk environment is used.

      • If device-mapper is output:

        Execute /sbin/dmsetup ls --tree to check the major and minor values of the device associated with the major and minor values displayed in b..

        Display example:

        # /sbin/dmsetup ls --tree
        system-usr (252:3)
          |- (251:2)
        system-var (252:4)
          |- (251:2)
        system-swap (252:1)
          |- (251:2)
        system-root (252:0)
          |- (251:2)
        system-tmp (252:2)
          |- (251:2)
        #

        If the major and minor values in b. are 252 and 0 respectively, then, in the example above, the corresponding device is (251:2), which has major and minor values of 251 and 2 respectively.

        Execute the following command with the major value specified for the argument:

        /bin/cat /proc/devices | /bin/grep -w {major}

        If sddlmfdrv is output, the HDLM boot disk environment is used.

        If sddlmfdrv is not output, the HDLM boot disk environment is not used.

      • If another device is output:

        The HDLM boot disk environment is not used.