x86: Advanced GRUB Administration and Troubleshooting

The following information is provided in this section:

• x86: Installing GRUB 2 by Using the bootadm install-bootloader Command

• x86: How to Install GRUB Legacy on a System That Has GRUB 2 Installed

x86: Installing GRUB 2 by Using the bootadm install-bootloader Command

If the GRUB 2 boot loader becomes corrupted, and the system can no longer boot, you might be required to boot from media and manually reinstall the boot loader. To reinstall the boot loader, you must boot from the Oracle Solaris installation media (for example, by using the text installer ISO image) and get to a command prompt.

x86: How to Install the Boot Loader

You must import the root pool before you can reinstall GRUB 2. The following procedure describes the steps to follow.

1. Assume the root role.

   See How to Use Your Assigned Administrative Rights in Oracle Solaris 11.1 Administration: Security Services.

2. Boot the system from the Oracle Solaris media.
3. Import the root pool.

   # zpool import -f pool-name

4. Install the boot loader.

   # bootadm install-bootloader [-f] -P pool-name

   -f

   Forces the installation of the boot loader an bypasses any versioning checks for not downgrading the version of the boot loader on the system.

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   Note - Do not used the -f option unless you are sure that you want to overwrite the boot loader with the version that is on the media.

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   -P

   Specifies the boot configuration for the pool to be used

5. Export the root pool.

   # zpool export pool-name

6. Reboot the system.

x86: How to Install the Boot Loader After Restoring a Root Pool

Before You Begin

Check that you are running the latest version of Oracle Solaris that is installed in the set of boot environments that is present in your backup. Making sure that you are running the latest version of Oracle Solaris that is installed in the set of boot environments that is present in your backup ensures that you can successfully install the boot loader by using the bootadm install-bootloader command, without requiring the use of the -f option.

Then, restore the root pool. See Chapter 11, Archiving Snapshots and Root Pool Recovery, in Oracle Solaris 11.1 Administration: ZFS File Systems.

• After restoring the root pool, install the boot loader on the constituent disks in the newly restored root pool.

  # bootadm install-bootloader -P poolname

  If you are not running the latest version of Oracle Solaris that is installed in the set of boot environments that is present in your backup, a restored rpool might fail to boot after running the bootadm install-bootloader command. In this instance, try running the following command as an alternative:

  # beadm activate -p poolname BEname

  where BEname is the boot environment that contains the latest version of Oracle Solaris. Running this command will install the latest boot loader files.

  This alternate method also installs the boot loader, but the installation is a side-effect of using the boot loader files from the boot environment, not from the running system. This workaround should be used when you are performing a restore from an older Oracle Solaris version.

x86: How to Install GRUB in a Location Other Than the Default Location

On systems with BIOS firmware, sometimes it is necessary or desirable to install GRUB 2 into the master boot record. The following procedure describes how to do so. After the installation, GRUB 2 is then the default system boot loader, regardless of which DOS partition is marked as the active partition. When DOS partitioning is used on systems with BIOS firmware, and the Solaris partition is a primary partition, the default GRUB 2 installation location is the partition boot record. If the partition is a logical partition, GRUB 2 is always installed in the MBR.

1. Assume the root role.

   See How to Use Your Assigned Administrative Rights in Oracle Solaris 11.1 Administration: Security Services.

2. Install the boot loader into the MBR location.

   # bootadm install-bootloader -M

3. Reboot the system.

x86: Installing GRUB Legacy on a System That Has GRUB 2 Installed

Because the system does not automatically reinstall the GRUB Legacy boot loader when you destroy the last GRUB 2 boot environment, if you want to reinstall the GRUB Legacy boot loader, you must first boot to the latest boot environment that includes the GRUB Legacy boot loader files (in /boot/grub/stage1 and /boot/grub/stage2).

The installgrub command is deprecated in this release and should only be used if you are running a release that supports the GRUB Legacy boot loader. See installgrub(1M).

x86: How to Install GRUB Legacy on a System That Has GRUB 2 Installed

The following procedure applies if you have upgraded your system from a release that supports GRUB Legacy to Oracle Solaris 11.1.

If you decide to revert your system to the older GRUB Legacy boot loader, use the following procedure.

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Caution - Be sure to perform these steps from the boot environment that contains the Oracle Solaris release or a Support Repository Update (SRU) that you used to update to Oracle Solaris 11.1. Additionally, if you have upgraded the ZFS pool's capabilities by using the zpool upgrade command past version 33, you will not be able to downgrade to GRUB Legacy or complete Step 2 of this procedure. Forcibly downgrading to GRUB Legacy after the root pool has been upgraded past version 33 results in an unbootable system.

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1. Assume the root role.

   See How to Use Your Assigned Administrative Rights in Oracle Solaris 11.1 Administration: Security Services.

2. Boot from the boot environment that was upgraded to the Oracle Solaris 11.1 release.
3. Remove all of the GRUB 2 boot environments from the system by using the beadm destroy command. See Destroying a Boot Environment in Creating and Administering Oracle Solaris 11 Boot Environments.

   Performing this step ensures that you do not accidentally activate and install GRUB 2, as activating any boot environments that include the Oracle Solaris 11.1 release will replace the Legacy GRUB boot loader with GRUB 2.

4. On the boot environment that contains the latest GRUB Legacy version, forcibly reinstall GRUB Legacy on the system, as follows:

   # bootadm install-bootloader -f

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   Note - You do not need to reboot after these steps. On the next full reboot, the GRUB Legacy boot loader will execute.

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