Extend VM's LVM with a new disk
Virtual machines created from templates usually have their file systems mounted over LVM. This allows to add more disks and to extend directly the
You can check it with:
# df -h / S.ficheros Size Used Avail Use% Mounted in /dev/mapper/Ubuntu14--vg-root 8,5G 6,3G 1,8G 79% /
/dev/mapper. In this case
/dev/mapper/Ubuntu14--vg-root is a LVM logical volume named
root in the volume group
To see which physical devices belong to the volume group use:
# pvs PV VG Fmt Attr PSize PFree /dev/sda5 Ubuntu14-vg lvm2 a-- 9,76g 0
In this case the volume group is formed by just one partition of disk
/dev/sda. A volume group can be composed of partitions and/or full disks.
We will add a new disk and use it wholly without partitioning to extend the logical volume
After adding a data disk in the Cloudstack interface, system should have a new unpartitioned disk available:
# cat /proc/partitions major minor #blocks name 253 0 5242880 vda 11 0 1048575 sr0 8 0 10485760 sda 8 1 248832 sda1 8 2 1 sda2 8 5 10233856 sda5 252 0 9183232 dm-0 252 1 1048576 dm-1
Depending on the system, it may be necessary to reboot the VM for it to discover the new disk.
sda is the system disk and is already partitioned.
sr0is the virtual CD-ROM. So the just added disk is
vda (note that it also matches in size).
Once identified the new disk, the first step is to create a physical lvm volume:
# pvcreate /dev/vda Physical volume "/dev/vda" successfully created
Then the just created physical volume is added to the volume group
# vgextend Ubuntu14-vg /dev/vda Volume group "Ubuntu14-vg" successfully extended
All the free space in the volume group is added to the logical volume:
# lvextend -l +100%FREE /dev/mapper/Ubuntu14--vg-root Extending logical volume root to 13,75 GiB Logical volume root successfully resized
Lastly, the filesystem in the logical volume must be resized. In our case, it can be done online because ext4 is used:
# resize2fs /dev/mapper/Ubuntu14--vg-root resize2fs 1.42.9 (4-Feb-2014) Filesystem at /dev/mapper/Ubuntu14--vg-root is mounted on /; on-line resizing required old_desc_blocks = 1, new_desc_blocks = 1 The filesystem on /dev/mapper/Ubuntu14--vg-root is now 3605504 blocks long.
Now, the system will have the added space in
# df -h / S.ficheros Tamaño Usados Disp Uso% Montado en /dev/mapper/Ubuntu14--vg-root 14G 6,3G 6,5G 50% /
This operation can be repeated with different volumes to enlarge even more the partition space.