Expand a Hard Disk with Ubuntu LVM

Expand a Hard Disk with Ubuntu LVM

So you’re running an Ubuntu server in a virtual machine, and now you need to add 20 GB of disk space to root (/). There are quite a few ways to do this, and fortunately you’re running the Logical Volume Manager (LVM) in Ubuntu, so the process isn’t too bad.

(This example uses Ubuntu Server 10.04, but it works for 12.04, 14.04, and 16.04 as well.)

After you make the additional space available in VMWare/Xen/Hyper-V, first reboot your Ubuntu server so it can see the new free space (commenter Michal notes that you can avoid this restart by asking the kernel to rescan the disk with ‘echo 1 > /sys/class/block/sda/device/rescan’). Then we’ll run the GNU partition editor to examine our disk:

root@myserver:/# parted
GNU Parted 2.2
Using /dev/sda
Welcome to GNU Parted! Type ‘help’ to view a list of commands.
(parted) print free
Model: VMware Virtual disk (scsi)
Disk /dev/sda: 42.5GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number Start End Size Type File system Flags
32.3kB 32.8kB 512B Free Space
1 32.8kB 255MB 255MB primary ext2 boot
255MB 255MB 8192B Free Space
2 255MB 16.1GB 15.8GB extended
5 255MB 16.1GB 15.8GB logical lvm
3 16.1GB 21.5GB 5365MB primary
21.5GB 21.5GB 6856kB Free Space
21.5GB 42.5GB 21.0GB Free Space <------
You can see your free space, so let’s partition it:

$ cfdisk
Pick your free space, select New, then choose a Primary or Logical partition. For a small server, it probably doesn’t matter too much, but remember in x86 Linux that you can have a maximum of 4 primary + extended partitions per disk. Beyond that, you’ll need to begin adding logical partitions in your extended partitions.

Select the Write command to create the partition, then (if necessary) reboot your system.

When your system comes back up, check on your new partition:

$ fdisk -l /dev/sda

Disk /dev/sda: 42.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000d90ee

Device Boot Start End Blocks Id System
/dev/sda1 * 1 31 248832 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 31 1958 15476768 5 Extended
/dev/sda3 1958 2610 5239185 83 Linux
/dev/sda4 2610 3608 16815191 83 Linux <-----
/dev/sda5 31 1958 15476736 8e Linux LVM
So now let’s pull it into our LVM configuration. First we’ll create the physical volume

$ pvcreate /dev/sda4
Physical volume “/dev/sda4” successfully created
Let’s take a look at our physical volumes:

$ pvdisplay

— Physical volume —
PV Name /dev/sda5
VG Name ubuntu-1004
PV Size 14.76 GiB / not usable 2.00 MiB
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 3778
Free PE 0
Allocated PE 3778
PV UUID f3tYaB-YCoK-ZeRq-LfDX-spqd-ggeV-gdsemo

— Physical volume —
PV Name /dev/sda3
VG Name ubuntu-1004
PV Size 5.00 GiB / not usable 401.00 KiB
Allocatable yes
PE Size 4.00 MiB
Total PE 1279
Free PE 11
Allocated PE 1268
PV UUID rL0QG1-OmuS-d4qL-d9u3-K7Hk-4a1l-NP3DtQ

“/dev/sda4” is a new physical volume of “20.00 GiB”
— NEW Physical volume —
PV Name /dev/sda4
VG Name
PV Size 20.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID uaJn0v-HbRz-YKv4-Ez83-jVUo-dfyH-Ky2oHV
Now, extend our volume group (ubuntu-1004) into our new physical volume (/dev/sda4):

$ vgextend ubuntu-1004 /dev/sda4
Volume group “ubuntu-1004” successfully extended
The whole purpose of this exercise is to expand the root filesystem, so let’s find our main logical volume:

$ lvdisplay

— Logical volume —
LV Name /dev/ubuntu-1004/root
VG Name ubuntu-1004
LV UUID UJQUwV-f3rI-Tsd3-dQYO-exIk-LSpq-2qls13
LV Write Access read/write
LV Status available

open 1

LV Size 19.39 GiB
Current LE 1892
Segments 1
Allocation inherit
Read ahead sectors auto

  • currently set to 256
    Block device 254:0
    Now, let’s extend the logical volume to all free space available:

$ lvextend -l+100%FREE /dev/ubuntu-1004/root
Next, extend the filesystem:

$ resize2fs /dev/mapper/ubuntu–1004-root
Finally, let’s check our free space:

$ df -h
Filesystem Size Used Avail Use% Mounted on
39G 14G 24G 37% / <----
none 495M 176K 495M 1% /dev
none 500M 0 500M 0% /dev/shm
none 500M 36K 500M 1% /var/run
none 500M 0 500M 0% /var/lock
none 500M 0 500M 0% /lib/init/rw
/dev/sda1 228M 144M 72M 67% /boot

Read more at http://www.geoffstratton.com/expand-hard-disk-ubuntu-lvm#umbTHgohPCZOov72.99