After increasing the size of my Ubuntu 12.04 LTS VM's OS disk by editing the guest VM's settings through the vSphere client, I do not see the increase in disk size when I check from within the OS (df -h).
On a windows VM I went into disk manager and extended the volume to use the unallocated space (created by increasing the disk size). How do I ensure that the OS sees this disk space increase in Linux?
The expanded disk size is unallocated and unpartitioned. You'll need to partition the new disk space first using fdisk or diskpart. After that, you may need to format the new partition. Depending on what kind of filesystem you're using, the commands will differ, but as an example, for ext3 you would call mkfs.ext3 Then depending on the OS, you'll be able to grow the logical volume. If you're using LVM, you can simply expand the original volume after you've partitioned/initialized the new space.
The below steps extended my partition from 12G to 26GB on a VMWare EXSi 5.5 running Centos 6 EXT4 VPS.
1) Identify the device name, which is by default /dev/sda, and confirm the new size by running the command:
# fdisk -l
2) Get list of partitions for /dev/sda device:
# ls -al /dev/sda*
brw-rw---- 1 root disk 8, 0 Dec 29 15:32 /dev/sda
brw-rw---- 1 root disk 8, 1 Dec 29 15:32 /dev/sda1
brw-rw---- 1 root disk 8, 2 Dec 29 15:32 /dev/sda2
3) Create new primary partition
# fdisk /dev/sda
Then type:
n (enter) [create new partition]
p (enter) [primary partition]
3 (enter) [next available number from listed /dev/sda partitions in 2)
(enter) [start cylinder]
(enter to use all available physical space) or specify size in +cylinders, +size{K,M,G}
t (enter) [change partition type]
3 (enter) [selecting /dev/sda3 partition]
8e (enter) [this sets partition type to Linux LVM or type L then enter to see list of types]
w (enter)
The partition table has been altered!
4) Reboot Centos 6.X then log back in with root privileges
# reboot
5) Check the new partition is ready and type '8e':
# fdisk -l
Device Boot Start End Blocks Id System
/dev/sda1 * 1 64 512000 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 64 2089 16264192 8e Linux LVM
/dev/sda3 2089 3916 14678054 8e Linux LVM
6) Create physical volume:
# pvcreate /dev/sda3
Physical volume "/dev/sda3" successfully created
7) Find out volume group name:
# vgdisplay
--- Volume group ---
VG Name vg_app1
...
8) Extend the physical volume:
# vgextend vg_app1 /dev/sda3
Volume group "vg_app1" successfully extended
9) Extend the existing volume group to the new physical volume (+100%FREE can be altered to desired size). Since we are extending root partition hence pointing to lv_root in vg_app1 volume group.
# lvextend -l +100%FREE /dev/vg_app1/lv_root
Size of logical volume vg_app1/lv_root changed from 11.63 GiB (2978 extents) to 25.63 GiB (6561 extents).
Logical volume lv_root successfully resized
10) Resize logical root volume:
# resize2fs /dev/vg_app1/lv_root
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/vg_app1/lv_root is mounted on /; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 2
Performing an on-line resize of /dev/vg_app1/lv_root to 6718464 (4k) blocks.
The filesystem on /dev/vg_app1/lv_root is now 6718464 blocks long.
Note: Use ext2online instead of resize2fs if it is a Red Hat virtual machine.
11) Check available space:
# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_app1-lv_root
26G 10G 14G 42% /
tmpfs 9.8G 0 9.8G 0% /dev/shm
/dev/sda1 477M 88M 364M 20% /boot
