Error: Mirror pools must be defined

The following error message occurred while creating a mirrored logical volume:

# mklv -c 2 -t jfs2 datavg01 10
0516-1814 lcreatelv: Mirror pools must be defined for each copy when strict mirror
        pools are enabled.
0516-822 mklv: Unable to create logical volume.
#

The reason for this is that the mirror pool strictness is set for the volume group. The article Mirror Pools: Understanding Mirror Pool Strictness examines and explains this in more detail.

Error: Every mirror pool must contain a copy of the logical volume

The attempt to create an unmirrored LV in a VG with mirror pools results in the following error:

# mklv -t jfs2 -p copy1=DC1 datavg01 10
0516-1829 mklv: Every mirror pool must contain a copy of
        the logical volume.
0516-822 mklv: Unable to create logical volume.
#

The cause is the VG‘s Mirror Pool Strictness attribute, which is set to ‘super-strict‘. The article Mirror Pools: Understanding Mirror Pool Strictness examines the importance of Mirror Pool Strictness using examples.