What command mirrors all the logical volumes that exist on a given volume group?

The command that mirrors all the logical volumes on a given volume group is "mirrorvg." This command is part of the Logical Volume Manager (LVM) system in Linux, specifically designed to manage and maintain logical volumes efficiently. When executed, mirrorvg will create mirrored copies of all logical volumes within the specified volume group, enhancing data redundancy and improving fault tolerance.

Utilizing this command is particularly valuable in environments where data integrity and availability are critical. By mirroring logical volumes, it ensures that if one copy of the data becomes unavailable due to hardware failure, the other mirrored copy can be accessed seamlessly, thereby minimizing the risk of data loss.

The other options provided serve different purposes within the LVM or related systems. For example, "lvcreate" is used to create new logical volumes but does not mirror existing ones. "vgchange" is used to change the attributes of a volume group and does not handle mirroring. The command "mirror" does not exist in standard LVM command sets and may cause confusion in this context. Thus, "mirrorvg" is the clear and correct choice for mirroring logical volumes in a volume group.