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Mirroring an encapsulated root disk

VxVM allows you to mirror the root volume and other areas needed for booting onto another disk. This makes it possible to recover from failure of your root disk by replacing it with one of its mirrors.

 To mirror your root disk onto another disk

1. Choose a disk that is at least as large as the existing root disk.
2. If the selected disk is not already under VxVM control, use the vxdiskadd or vxdiskadm command, or the Veritas Enterprise Administrator (VEA) to add it to the bootdg disk group. Ensure that you specify the sliced format for the disk.
3. Select menu item 6 (Mirror Volumes on a Disk) from the vxdiskadm main menu, or use the VEA to create a mirror of the root disk. (These automatically invoke the vxrootmir command if the mirroring operation is performed on the root disk.)

   Alternatively, to mirror only those file systems on the root disk that are required to boot the system, run the following command:

   # /etc/vx/bin/vxrootmir altboot_disk

   where altboot_disk is the disk media name of the mirror for the root disk. vxrootmir creates a mirror for rootvol (the volume for the root file system on an alternate disk). The alternate root disk is configured to enable booting from it if the primary root disk fails.

4. Set the value of the EEPROM variable use-nvramrc? to true. This enables the use of VxVM boot disk aliases, which identify mirrors of the root disk from which the system can be booted. If the system is up and running, set use-nvramrc? to true using the following command:

   # eeprom use-nvramrc?=true

   You can also set use-nvramrc? at the ok boot prompt:

   ok setenv use-nvramrc? true

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

   You can use the devalias command at the boot prompt to discover the alternate disks from which the system may be booted:

   ok devalias