LVM

Logical Volume Manager

How to expand existing root partition using LVM

Add a second physical drive.  Scan the system, no reboot needed:
echo "- - -" > /sys/class/scsi_host/host1/scan

Create Logic Group and Volume:

pvcreate datavg /dev/sdb1
vgcreate datavg /dev/sdb1
lvcreate -l 100%FREE -n lvdata datavg

# vgdisplay
  --- Volume group ---
  VG Name               datavg
  System ID             
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  2
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               59.99 GiB
  PE Size               4.00 MiB
  Total PE              15358
  Alloc PE / Size       15358 / 59.99 GiB
  Free  PE / Size       0 / 0   
  VG UUID               zWlhGf-YDZa-27xv-aH0t-F6fW-Hs1e-TY3d8t

mkfs.ext3 -m 0 /dev/datavg/lvdata
tune2fs -c0 /dev/datavg/lvdata


Expand existing root LVM partition

pvdisplay
pvcreate /dev/sdb1
vgextend root_partition_name /dev/sdb1
lvextend -l +100%FREE /dev/root_partition_name/root

resize2fs /dev/root_partition_name/root

If you need to reduce it back:

vgreduce -a root_partition_name