Swap is most efficient if it is interleaved between two or more disks. For maximum efficiency each swap area should have equal priority and should be the same size (so one doesn't run out before the other)

 1. lvcreate -C y -L size -r n -n name /dev/vg_name
 2. swapon /dev/vg_name/lv_name (priority defaults to 1)
 3. update /etc/fstab, e.g.
    /dev/vg02/swap2 / swap defaults 0 0