You can unmirror the root volume group.

Attention: Unmirroring the root volume group requires advanced system administration experience. If not done correctly, your system can become unbootable.

In the following scenario, the root volume group is on hdisk01 and mirrored onto hdisk11. This example removes the mirror on hdisk11. The procedure is the same, regardless of which disk you booted to last.

1. Use the following command to unmirror the root volume group on hdisk11:

unmirrorvg rootvg hdisk11

The unmirrorvg command turns quorum back on for the root volume group.

1. Use the following command to reduce the disk out of the root volume group:

reducevg rootvg hdisk11

1. Use the following command to reinitialize the boot record of the remaining disk:

bosboot -a -d /dev/hdisk01

1. Use the following command to modify the boot list in order to remove the unmirrored disk from the list:

bootlist -m normal hdisk01

The disk is unmirrored.

Mirror Procedure:

The following steps assume the user has rootvg contained on hdisk0 and is

attempting to mirror the rootvg to a new disk hdisk1.

1. Extend rootvg to hdisk1:

extendvg rootvg hdisk1

If the user encounters the error message:

0516-050 Not enough descriptor space left in this volume group.

Either try adding a smaller PV or use another volume group.

Then the user may not add hdisk1 to rootvg for mirroring. The user may

attempt to mirror rootvg’s logical volumes to another disk that

already exists in rootvg and meets the criteria and restrictions

listed in the “restrictions” section above. The user may also attempt

to add a smaller disk to the rootvg. If neither option is possible,

then mirroring rootvg cannot be performed on this system.

2. Disable QUORUM, by running the following:

chvg -Qn rootvg

3. Mirror the logical volumes that make up the AIX operating system:

mklvcopy hd1 2 hdisk1 # /home file system

mklvcopy hd2 2 hdisk1 # /usr file system

mklvcopy hd3 2 hdisk1 # /tmp file system

mklvcopy hd4 2 hdisk1 # / (root) file system

mklvcopy hd5 2 hdisk1 # blv, boot logical volume

mklvcopy hd6 2 hdisk1 # paging space

(if the user has other paging devices, rootvg and non-rootvg, they

must also mirror those logical volumes in addition to hd6)

mklvcopy hd8 2 hdisk1 # file system log

mklvcopy hd9var 2 hdisk1 # /var file system

If hd5 consists of more than one logical partition, then after

mirroring hd5 the user must verify that the mirrored copy of hd5

resides on contiguous physical partitions. This can be verified with

the command:

lslv -m hd5

If the mirrored hd5 partitions are not contiguous, then the user must

delete the mirror copy of hd5 (on hdisk1) and rerun the mklvcopy for

hd5 using the “-m” option. The user should consult documentation on

the usage of the “-m” option for mklvcopy.

4. Synchronize the newly created mirrors:

syncvg -v rootvg

5. Bosboot to initialize all boot records and devices:

bosboot -a

6. Initialize the boot list:

bootlist -m normal hdisk0 hdisk1

Warning: Even though this command identifies the list of possible boot

disks it does not guarantee that the system will boot from the

alternate disk in all cases involving failures of the first disk. In

such situations, it may be necessary for the user to boot from the

installation/maintenance media, select maintenance, reissue the

bootlist command leaving out the failing disk, and then reboot. On

some models, firmware provides a utility for selecting the boot device

at boot time. This may also be used to force the system to boot from

the alternate disk.

7. Shutdown and reboot the system:

shutdown -Fr

This is so that the “Quorum OFF” function takes effect.