Booting from an alternate boot disk on Sun SPARC systems

If the root disk is encapsulated and mirrored, you can use one of its mirrors to boot the system if the primary boot disk fails.

On a Sun SPARC system, booting from an alternate boot disk requires that some EEPROM settings are changed.

The boot process on SPARC systems

A Sun SPARCŪ system prompts for a boot command unless the autoboot flag has been set in the nonvolatile storage area used by the firmware. Machines with older PROMs have different prompts than that for the newer V2 and V3 versions. These newer versions of PROM are also known as OpenBoot PROMs (OBP). The boot command syntax for the newer types of PROMs is:

  ok boot [OBP names] [filename] [boot-flags]

The OBP names specify the OpenBoot PROM designations. For example, on Desktop SPARC systems, the designation sbus/esp@0,800000/sd@3,0:a indicates a SCSI disk (sd) at target 3, lun 0 on the SCSI bus, with the esp host bus adapter plugged into slot 0.

You can use Veritas Volume Manager boot disk alias names instead of OBP names. Example aliases are vx-rootdisk or vx-disk01. To list the available boot devices, use the devalias command at the OpenBoot prompt.

The filename argument is the name of a file that contains the kernel. The default is /kernel/unix in the root partition. If necessary, you can specify another program (such as /stand/diag) by specifying the -a flag. (Some versions of the firmware allow the default filename to be saved in the nonvolatile storage area of the system.)

Warning:

Do not boot a system running VxVM with rootability enabled using all the defaults presented by the -a flag.

Boot flags are not interpreted by the boot program. The boot program passes all boot-flags to the file identified by filename.

See the kadb (1M) manual page.

See the kernel (1) manual page.

Defining a root disk mirror as bootable

After creating a root disk mirror, you can make it available for booting.

To define a root disk mirror as bootable on a SPARC system

  1. Check that the EEPROM variable use-nvramrc? is set to true. Enter the following command at the boot prompt:

    ok printenv use-nvramrc?

    If the system is up and running, enter the following command:

    # eeprom use-nvramrc?

    If use-nvramrc? is set to true, this allows the use of alternate boot disks.

    If use-nvramrc? is set to false, the system fails to boot from the devalias and displays an error message such as the following:

      Rebooting with command: boot vx-mirdisk
      Boot device: /pci@1f,4000/scsi@3/disk@0,0 File and args:vx-
      mirdisk
      boot: cannot open vx-mirdisk
      Enter filename [vx-mirdisk]:
  2. Set the value of use-nvramrc? to true.

    At the ok boot prompt, enter:

    ok setenv use-nvramrc? true

    If the system is up and running, use the following command:

    # eeprom use-nvramrc?=true
  3. Define an alternate boot disk by entering the following command at the ok boot prompt:

    ok nvramrc=devalias vx-altboot_disk

    where altboot_disk is the device name of an alternate disk from which the system can be booted.

    If the system is already up and running, enter the following command to define an alternate boot disk:

    # eeprom nvramrc=devalias vx-altboot_disk
  4. Use the devalias command at the boot prompt to discover the alternate disks from which the system may be booted:

    ok devalias

    Suitable mirrors of the root disk are listed with names of the form vx-diskname.

  5. You should now be able to boot the system from an alternate boot disk, vx-altboot_disk, by entering the following command at the ok boot prompt:

    ok boot vx-altboot_disk

    If a selected disk contains a root mirror that is stale, vxconfigd displays an error stating that the mirror is unusable and lists any non-stale alternate bootable disks.

More Information

The boot process on SPARC systems