Create and resize LVM partition

Resize existing partition:

/usr/sbin/lvresize -L 68G /dev/VolGroup00/LogVol00
  Extending logical volume LogVol00 to 68GB
  Logical volume LogVol00 successfully resized

Create new volume:

/usr/sbin/lvcreate -L 4GB -n rhel5 my_vol_grp VolGroup00

/usr/sbin/lvdisplay

mke2fs -j /dev/VolGroup00/rhel5
mount /dev/VolGroup00/rhel5 /mnt/rhel5

add to /etc/fstab:

/dev/VolGroup00/rhel5   /mnt/rhel5    ext3    
defaults   1 3 

** Physical Partition needs to be resized as well or your HD will crash :-) Mine did!