cheat sheets.

Creating new PV for LVM
  pvcreate /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1

Removing PV from LVM
  pvremove /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1

Showing info
  pvdisplay
  lvdisplay
  vgdisplay
  lvs
  pvs
  vgs
  vgscan
  lvscan
  pvscan

Creating VG "fileserver" and add to it our PV
  vgcreate fileserver /dev/sdb1 /dev/sdc1 /dev/sdd1

Extending VG "fileserver" by additional PV
  vgextend fileserver /dev/sde1

Copying data from one PV to other PV
  pvmove /dev/sdb1 /dev/sde1

Removing one PV from VG "fileserver" 
(first you need to move data from this PV to another PV)
  vgreduce fileserver /dev/sdb1

Renaming VG
  vgrename fileserver data

Removing VG
  vgremove data

Creating 1GB LV "media" in "fileserver" VG
  lvcreate --name media --size 1G fileserver

Creating a filesystem in our LV
  mkfs.ext4 /dev/fileserver/media

Extending our LV from 1GB to 1.5GB
  lvextend -L1.5G /dev/fileserver/media

Checking LV filesystem
  e2fsck -f /dev/fileserver/media
Extending LV filesystem
  resize2fs /dev/fileserver/media
Shrinking LV filesystem
  resize2fs /dev/fileserver/media <nr-of-blocks>

Shrinking our LV from 1.5GB to 1GB
(Shrinking a logical volume is the other way round: first we must shrink the
filesystem before we reduce the logical volume's size)
  lvreduce -L1G /dev/fileserver/media

Mounting LV
  mkdir /var/media 
  mount /dev/fileserver/media /var/media
  df -h

Renaming LV from "fileserver" VG
  lvrename fileserver media films

Removing LV from "fileserver" VG
  lvremove /dev/fileserver/films




Creating a snapshot:
  lvcreate --size <snapsize> -s --name <snapname> <root-volume>



source: http://www.howtoforge.com/linux_lvm_p6