from http://www.redhatlinux.info/2010/11/lvm-logical-volume-manager.html

LVM (LOGICAL VOLUME MANAGER) 1. TO CREATE LVM

1.fdisk /dev/sda   ->create 3 partitions + label to 8e
2.partprobe
3.fdisk -l
4.pvcreate /dev/sda8 /dev/sda9
5.pvdisplay /dev/sda8
6.pvdisplay /dev/sda9
7.vgcreate vg0 /dev/sda8 /dev/sda9
8.vgdisplay 
9.lvcreate -L +200M -n /dev/vg0/home1
10.lvdisplay /dev/vg0/home1
11.lvcreate -L +300M -n /dev/vg0/var1
12.lvdisplay /dev/vg0/var1 
13.mkfs.ext3 /dev/vg0/var1
14 mkfs.ext3 /dev/vg0/home1 
15.mkdir /home1
16.mkdir /var1
17.mount /dev/vg0/home1 /home1
18.mount /dev/vg0/var1 /var1
19.cp /etc/a* /home1
20.cp /etc/b* /var1
21.vim /etc/fstab 
22.mount -a

TO EXTEND LVM

1.lvdisplay /dev/vg0/home1
2.lvextend -L +200M /dev/vg0/home1
3.ls /home1
4.resize2fs /dev/vg0/home1
5.ls /home1

TO REDUCE LVM

1. lvdisplay 
2. umount /var1
3. e2fsck -f /dev/vg0/var1
4. resize2fs /dev/vg0/var1 100M
5. lvreduce -L -100M -n /dev/vg0/var1
6. mount /dev/vg0/var1 /var1
7. df -h 

LVM SNAPSHOT

1.  lvcreate  -L 200M -s -n lv2 /dev/llc/lv1

TO EXTEND PV 1.pvcreate /dev/sda10 2.pvdisplay

TO EXTEND VG 1.vgextend vg0 /dev/sda10 2.vgdisplay vg0

TO REDUCE VG 1.vgreduce vg0 /dev/sda10 2.vgdisplay

TO REDUCE PV 1.pvremove /dev/sda10 2.pvdisplay

REMOVE LVM 1.lvdisplay 2.umount /dev/vg0/home1 3.umount /dev/vg0/var1 4.vim /etc/fstab 5.lvremove /dev/vg0/home1 6.lvremove /dev/vg0/var1 7.lvdisplay

REMOVE VG 1.vgdisplay 2.vgremove /dev/vg0 3.vgdisplay

REMOVE PV 1.pvdisplay 2.pvremove /dev/sda9 3.pvremove /dev/sda8

---

from http://www.linux-mag.com/cache/7454/1.html

# fdisk -l /dev/sdb

Disk /dev/sdb: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1       30400   244187968+  8e  Linux LVM
/dev/sdb2           30401       60801   244196032+  8e  Linux LVM
   

# pvcreate /dev/sdb1 /dev/sdb2 /dev/sdc1 /dev/sdc2
Physical volume "/dev/sdb1" successfully created
Physical volume "/dev/sdb2" successfully created
Physical volume "/dev/sdc1" successfully created
Physical volume "/dev/sdc2" successfully created


# pvdisplay


# vgcreate primary_vg /dev/sdb1 /dev/sdb2 /dev/sdc1 /dev/sdc2
  Volume group "primary_vg" successfully created


# vgdisplay

# vgscan
Reading all physical volumes.  This may take a while...
Found volume group "primary_vg" using metadata type lvm2
  
# lvcreate --name /dev/primary_vg/home_lv --size 450G
  Logical volume "home_lv" created

# lvdisplay

# lvscan

# mkfs.ext3 /dev/primary_vg/home_lv


# lvcreate -L500M -s -n home_backup_080309 /dev/primary_vg/home_lv
  Logical volume "home_backup_080309" created


# lvscan
  ACTIVE   Original '/dev/primary_vg/home_lv' [450.00 GB] inherit
    ACTIVE   Snapshot '/dev/primary_vg/home_backup_080309' [500.00 MB] inherit


# mkdir /mnt/backup/home_backup_080309
# mount /dev/primary_vg/home_lv/home_backup_080309 /mnt/backup/home_backup_080309
# mount
/dev/hda3 on / type ext3 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
/dev/hda1 on /boot type ext2 (rw)
tmpfs on /dev/shm type tmpfs (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
/dev/mapper/primary_vg-home_lv on /home type ext3 (rw,data=ordered)
/dev/mapper/primary_vg-home_backup_080309 on /mnt/backup/home_backup_080309 type ext3 (rw)

# ls -s /mnt/backup/home_backup_080309/
total 20
16 lost+found   4 user5
# ls -s /mnt/backup/home_backup_080309/user5
total 74080
    4 linux-2.6.30  74076 linux-2.6.30.tar.gz