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Solaris 10 8/07 Installation Guide: Solaris Live Upgrade and Upgrade Planning

Procedurex86: To Fall Back From a Failed Boot Environment Activation With the GRUB Menu

If you experience a failure while booting, use the following procedure to fall back to the original boot environment. In this example, the GRUB menu is displayed correctly, but the new boot environment is not bootable. The device is /dev/dsk/c0t4d0s0. The original boot environment, c0t4d0s0, becomes the active boot environment.

Caution – Caution –

For the Solaris 10 3/05 release, the recommended action to fall back if the previous boot environment and new boot environment were on different disks included changing the hard disk boot order in the BIOS. Starting with the Solaris 10 1/06 release, changing the BIOS disk order is unnecessary and is strongly discouraged. Changing the BIOS disk order might invalidate the GRUB menu and cause the boot environment to become unbootable. If the BIOS disk order is changed, reverting the order back to the original settings restores system functionality.

  1. Become superuser or assume an equivalent role.

    Roles contain authorizations and privileged commands. For more information about roles, see Configuring RBAC (Task Map) in System Administration Guide: Security Services.

  2. To display the GRUB menu, reboot the system.


    # init 6

    The GRUB menu is displayed.


    GNU GRUB version 0.95 (616K lower / 4127168K upper memory)
+-------------------------------------------------------------------+
|Solaris                                                            |
|Solaris failsafe                                                   |
|second_disk                                                        |
|second_disk failsafe                                               |
+-------------------------------------------------------------------+
Use the ^ and v keys to select which entry is highlighted. Press
enter to boot the selected OS, 'e' to edit the commands before
booting, or 'c' for a command-line.

  3. From the GRUB menu, select the original boot environment. The boot environment must have been created with GRUB software. A boot environment that was created before the Solaris 10 1/06 release is not a GRUB boot environment. If you do not have a bootable GRUB boot environment, then skip to this procedure, x86: To Fall Back From a Failed Boot Environment Activation With the GRUB Menu and the DVD or CD.

  4. Boot to single user mode by editing the Grub menu.

    1. To edit the GRUB main menu, type e.

      The GRUB edit menu is displayed.


      root (hd0,2,a)
kernel /platform/i86pc/multiboot
module /platform/i86pc/boot_archive

    2. Select the original boot environment's kernel entry by using the arrow keys.

    3. To edit the boot entry, type e.

      The kernel entry is displayed in the GRUB edit menu.


      grub edit>kernel /boot/multiboot

    4. Type -s and press Enter.

      The following example notes the placement of the -s option.


      grub edit>kernel /boot/multiboot -s

    5. To begin the booting process in single user mode, type b.

  5. If necessary, check the integrity of the root (/) file system for the fallback boot environment.


    # fsck mount_ point
    mount_point

    A root (/) file system that is known and reliable

  6. Mount the original boot environment root slice to some directory (such as /mnt): 


    # mount device_name /mnt
    device_name

    Specifies the location of the root (/) file system on the disk device of the boot environment you want to fall back to. The device name is entered in the form of /dev/dsk/cwtxdysz.

  7. From the active boot environment root slice, type:


    # /mnt/sbin/luactivate

    luactivate activates the previous working boot environment and indicates the result.

  8. Unmount /mnt.


    # umount /mnt

  9. Reboot. 


    # init 6

    The previous working boot environment becomes the active boot environment.