how to mount an lvm partition

LVM2 utilizes device mapper. So, poking around a drive with ls /dev/sd*, fdisk -l /dev/xxx, etc... will not give you the information required to manually mount a partition for maintenance. To determine the device mapper name required for a mount command run...

# dmsetup ls

Determine from that output what partition you want to mount.

# mount /dev/mapper/<something_from_dmsetup_output>