Booting in LPAR mode from DASD

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6.18 LPAR mode

Use the SE or HMC to boot Linux® in LPAR mode from a DASD boot device.

Before you begin

You need a boot device that is prepared with zipl.

Procedure

Perform these steps to boot from a DASD boot device:
  1. In the navigation pane of the HMC, expand Systems Management and select the hardware system that you want to work with. A table of LPARs is displayed on the Partitions tab in the content area.
  2. Select the LPAR where you want to boot Linux.
  3. In the Tasks area, expand Recovery and click Load. See Figure 1.
    Figure 1. Load task on the HMC

    Screen capture of the Hardware Management Console. In the Tasks area, expand the Recovery list and click Load.
  4. Proceed according to your hardware level to specify details about the load process.
    Follow these steps for IBM® z16® with the updates of May 2023.
    1. Select device type ECKD as shown in Figure 2.
      Figure 2. Load panel for booting from DASD with device type selection

      Screen capture of the Load panel with device type ECKD selected.
    2. Select the IPL type depending on the boot-data format on the boot device.
      • Select List-directed for the secure-boot enabled format.

        Optional: For boot images in the secure-boot format, select Enable secure boot. For more information about secure boot, see Secure boot.

      • Select Channel command word (CCW) otherwise. This selection corresponds to the traditional Standard load load type.
    3. Select load type Load an OS.
    4. Accept Use volume label for specifying the boot record location. If you need a specific location, select the option that enables the fields for cylinder, head, and record specifications and enter the values for your custom location.

      The boot loader needs to find the first data record (boot record) that marks the disk as bootable and describes where to find boot data on the disk. For ECKD, the location is noted in the volume label block (record 3 on disk) that is a standardized format data block available on all DASDs. The Use volume label setting tells the boot loader to look at the volume label to obtain the boot record location.

    5. Accept the Automatic default for the boot program selector.

      The Automatic setting tells the boot loader to use the first entry in the list of available programs that matches the boot type. For example, if there is a boot entry at index 7 and a dump entry at index 14, the Automatic setting boots index 7 if IPL is selected. Linux always installs a boot menu entry at index 0, which is a duplicate of the default boot menu entry.

    Note: Do not select the Clear main memory before loading check box unless you must clear memory. Memory clearing can considerably prolong the IPL procedure.
    For earlier hardware levels, select load type Standard load as shown in Figure 3.
    Figure 3. Load panel for booting from DASD

    Screen capture of the Load panel. Ensure that the Load type Standard load is selected.
    Note: Do not select the Clear the main memory on this partition before loading it check box unless you must clear memory. Memory clearing can considerably prolong the IPL procedure.
  5. Enter the device number of the DASD boot device in the Load address field.
    To IPL from a subchannel set other than 0, specify five digits: The subchannel set ID followed by the device number, for example 1E711.
  6. If the boot configuration is part of a zipl created menu configuration, type the configuration number that identifies your DASD boot configuration within the menu in the Load parameter field.

    Configuration number 0 specifies the default configuration. Depending on the menu configuration, omitting this option might display the menu or select the default configuration. Specifying prompt instead of a configuration number forces the menu to be displayed.

    When the menu is displayed, you can specify additional kernel parameters . These additional kernel parameters are appended to the parameters you might have provided in a parameter file. The combined parameter string must not exceed a length that is set when the kernel is compiled.

  7. If you want to boot your Linux instance in the context of a particular site, type the site specification in the Load parameter field. If applicable, append the specification to the menu selection without a blank. For more information about site-specific booting, see Site-specific Linux instantiation.
  8. Click OK to start the boot process.
  9. Optional: Check the output on the preferred console to monitor the boot progress.

DASD menu configuration example for LPAR

Use the Operating System Messages applet on the HMC or SE to choose a boot configuration from a menu configuration.

This example illustrates how menu2 in the sample configuration file in Menu configurations is displayed on the HMC or SE:

zIPL interactive boot menu

0. default (boot1)

1. boot1
2. boot3

Please choose (default will boot in 30 seconds): 2

You choose a configuration by specifying the configuration number. For example, to boot configuration boot3 specify 2.

You can also specify additional kernel parameters by appending them to the configuration number. For example, you can specify: 
2 maxcpus=1
These parameters are concatenated to the end of the existing kernel parameters that are used by your boot configuration when booting Linux.