Creating a LVM larger than 2TB on RHEL 5

You must use the entire disk. Example below:

#pvcreate /dev/sdb
#vgcreate BackupVolGroup /dev/sdb
#vgdisplay
  --- Volume group ---
  VG Name               BackupVolGroup
  System ID             
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  1
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                0
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               4.07 TB
  PE Size               4.00 MB
  Total PE              1067167
  Alloc PE / Size       0 / 0   
  Free  PE / Size       1067167 / 4.07 TB
  VG UUID               f0Uj23-6Bdz-dfK8-2pTz-m19f-wKAJ-s715b2


http://kbase.redhat.com/faq/docs/DOC-9855