x86: Falling Back to the Original Boot Environment

To fall back to the original boot environment, choose the procedure the best fits your circumstances.

x86: To Fall Back Despite Successful New Boot Environment Activation With the GRUB Menu

• If you are using the Solaris 10 3/05 release, do not use this procedure. Depending on your system, see one of the following procedures:

  • x86: To Fall Back With Boot Environments on Different Disks

  • x86: To Fall Back With Boot Environments on the Same Disk

• Starting with the Solaris 10 1/06 release, use this procedure when you have successfully activated your new boot environment, but are dissatisfied with the results. You can quickly switch back to the original boot environment by using the GRUB menu.

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  Note –

  The boot environments that are being switched must be GRUB boot environments that were created with GRUB software.

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Steps

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. Reboot the system.

   # init 6

   The GRUB menu is displayed. The Solaris OS is the original boot environment. The second_disk boot environment was successfully activated and appears on the GRUB menu. The failsafe entries are for recovery if for some reason the primary entry does not boot.

   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. To boot to the original boot environment, use the arrow key to select the original boot environment and press Return.

Example 10–1 To Fall Back Despite Successful New Boot Environment Activation

# su
# init 6

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.

Select the original boot environment, Solaris.

x86: To Fall Back From a Failed Boot Environment Activation With the GRUB Menu

• If you are using the Solaris 10 3/05 release, do not use this procedure. Depending on your systems, see one of the following procedures:

  • x86: To Fall Back With Boot Environments on Different Disks

  • x86: To Fall Back With Boot Environments on the Same Disk

• Starting with the Solaris 10 1/06 release, 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.

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.

Steps

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.

x86: To Fall Back From a Failed Boot Environment Activation With the GRUB Menu and the DVD or CD

• If you are using the Solaris 10 3/05 release, do not use this procedure. Depending on your systems, see one of the following procedures:

  • x86: To Fall Back With Boot Environments on Different Disks

  • x86: To Fall Back With Boot Environments on the Same Disk

• Starting with the Solaris 10 1/06 release, if you experience a failure while booting, use the following procedure to fall back to the original boot environment. In this example, the new boot environment was not bootable. Also, the GRUB menu does not display. The device is /dev/dsk/c0t4d0s0. The original boot environment, c0t4d0s0, becomes the active boot environment.

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.

Steps

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. Insert the Solaris Operating System for x86 Platforms DVD or Solaris Software for x86 Platforms - 1 CD.

3. Boot from the DVD or CD.

   # init 6

   The GRUB menu is displayed.

   GNU GRUB version 0.95 (616K lower / 4127168K upper memory) +-------------------------------------------------------------------+ |Solaris | |Solaris 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.

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 an editor.

      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 Do you want to fallback to activate boot environment c0t4d0s0 (yes or no)? yes

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

8. Unmount /mnt.

   # umount device_name

   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.

9. Reboot.

   # init 6

   The previous working boot environment becomes the active boot environment.

x86: To Fall Back Despite Successful New Boot Environment Activation

• Starting with the Solaris 10 1/06 release, do not use this procedure. See x86: To Fall Back Despite Successful New Boot Environment Activation With the GRUB Menu.

• For the Solaris 10 3/05 release, use this procedure when you have successfully activated your new boot environment, but are dissatisfied with the results.

Steps

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. Type:

   # /sbin/luactivate BE_name

   BE_name

   Specifies the name of the boot environment to be activated

3. Reboot.

   # init 6

   The previous working boot environment becomes the active boot environment.

x86: To Fall Back With Boot Environments on Different Disks

• Starting with the Solaris 10 1/06 release, do not use this procedure. See x86: To Fall Back From a Failed Boot Environment Activation With the GRUB Menu.

• For the Solaris 10 3/05 release, if the root (/) file systems for the boot environments are on different physical disks, use the following procedure to fall back to the original boot environment.

Steps

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. Reboot the machine and enter the appropriate BIOS menus.

   • If your boot devices are SCSI, refer to documentation on your SCSI controller on how to enter the SCSI BIOS.

   • If the boot devices are maintained by the system BIOS, refer to system BIOS documentation on how to enter the system BIOS.

3. Follow the appropriate BIOS documentation to change the boot device back to the original boot environment's boot device if different.

4. Save the BIOS changes.

5. Exit BIOS to begin the boot process.

6. Type b -s to boot the machine to single-user state.

7. Type:

   # /sbin/luactivate

8. Reboot.

   # init 6

x86: To Fall Back With Boot Environments on the Same Disk

• Starting with the Solaris 10 1/06 release, do not use this procedure. See x86: To Fall Back From a Failed Boot Environment Activation With the GRUB Menu

• For the Solaris 10 3/05 release, if the root (/) file systems are on the same physical disk, use the following procedure to fall back to the original boot environment. You need to mount the root (/) slice from the last-active boot environment. Then run the luactivate command, which makes the switch. When you reboot, the last-active boot environment is up and running again.

Steps

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. Decide how to boot the system.

   • If you boot from the Solaris Operating System DVD or the Solaris Software - 1 CD, insert the disc. Your system's BIOS must support booting from a DVD or CD.

   • If you boot from the network, use Preboot Execution Environment (PXE) network boot. The system must support PXE. Enable the system to use PXE by using the system's BIOS setup tool or the network adapter's configuration setup Tool.

   • If you boot from a diskette, insert Solaris 10 3/05 Device Configuration Assistant diskette into the system's diskette drive.

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     x86 only –

     You can copy the Device Configuration Assistant software to a diskette from the Solaris Operating System for x86 Platforms DVD or Solaris Software for x86 Platforms - 2 CD by using the procedure described in x86: (Optional) To Update the Boot Diskette Before Activating.

     ---

   Follow the directions onscreen until the Current Boot Parameters menu is displayed.

3. Type b -s to boot the machine to single-user state.

4. 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

5. Mount the active 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.

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

   # /mnt/sbin/luactivate

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

7. Unmount /mnt/sbin.

   # umount device_name

   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.

8. Reboot.

   # init 6

   The previous working boot environment becomes the active boot environment.