5.3.6. Activating and Mounting the Original Logical Volume
Since you had to deactivate the logical volume mylv, you need to activate it again before you can mount it.
root@tng3-1 ~]# lvchange -a y mylv [root@tng3-1 ~]# mount /dev/myvg/mylv /mnt [root@tng3-1 ~]# df Filesystem 1K-blocks Used Available Use% Mounted on /dev/yourvg/yourlv 24507776 32 24507744 1% /mnt /dev/myvg/mylv 24507776 32 24507744 1% /mnt