How to: Resize Linux osDisk partition on Azure
Most Linux images on Azure will by default have 30GB size for the osDisk and that is something that you might want to resize moving forward.
NOTE: We recommend to store applications and data on a separate data disk not only because of space but also for performance reasons.
Resizing the partition is really simple on Azure and we can be done by the following procedure:
a) Stopping and deallocating the VM on the portal or Azure CLI / PowerShell;
b) Editing the disk on the portal and setting the size to the desired value;
c) Updating the partition information within the Linux OS which might be slightly different depending on the partitions and distribution but the concept is very similar , which is basically deleting and recreating the root partition.
NOTE: You must create a backup or a snapshot of the VHD prior to the resizing steps , you can use https://storageexplorer.com or also AZCopy once the VM is deallocated when using unmanaged disks.
For managed disks, you can use the Azure Portal to create a snapshot of the disk.
Steps to make the required partition changes are listed below per distribution and have been tested in the specific releases listed:
For Red Hat 7.3 / CentOS 7.3 and Oracle 7.3:
1) Login to the VM using SSH, we can check the size of the disk by using:
sudo dmesg | grep -i sda
We should see something similar to the output below (assuming you changed the size to 100GB on the portal for the disk):
[ 3.100914] sd 2:0:0:0: [sda] 209715200 512-byte logical blocks: (107 GB/100 GiB)
2) To proceed with the partition resize, we will use:
sudo fdisk /dev/sda
type: p
this will show both partitions /dev/sda1 and /dev/sda2 which are basically partitions 1 and 2
type: d then 2 (to delete partition 2)
type: n then p, 2 (to recreate partition 2) you can accept the default values
type: w (to save the new partition)
type: q (to exit fdisk)
sudo reboot (to reboot the VM so the partition is updated)
3) To finalize the resize, after the reboot, execute the command:
For Red Hat 7.3 and CentOS 7.3:
sudo xfs_growfs /dev/sda2
For Oracle 7.3:
sudo btrfs filesystem resize max /
4) Use the command: df -h to verify its size:
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 100G 1.6G 98G 2% /
For Ubuntu 16.04 LTS:
No extra steps are necessary, simply deallocating the VM, changing the size on the portal and starting the VM backup will work. You can verify the size after the VM is up by using:
df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 97G 1.4G 96G 2% /
For Debian 8:
1) Login to the VM using SSH, we can check the size of the disk by using:
sudo dmesg | grep -i sda
We should see something similar to the output below (assuming you changed the size to 100GB on the portal for the disk):
[ 3.100914] sd 2:0:0:0: [sda] 209715200 512-byte logical blocks: (107 GB/100 GiB)
2) To proceed with the partition resize, we will use: sudo fdisk /dev/sda
type: p
this will show partition /dev/sda1
type: d
type: n then p, 1 (to recreate partition 1) you can accept the default values
NOTE: if you receive a message about deleting or keeping a signature on the disk, just answer N
type: w (to save the new partition)
type: q (to exit fdisk)
sudo reboot (to reboot the VM so the partition is updated)
3) To finalize the resize, after the reboot, execute the command: resize2fs /dev/sda1
4) Use the command: df -h to verify its size:
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 99G 698M 94G 1% /
For SUSE 12 SP2 (Premium):
1) Login to the VM using SSH, we can check the size of the disk by using:
sudo dmesg | grep -i sda
We should see something similar to the output below (assuming you changed the size to 100GB on the portal for the disk):
[ 3.100914] sd 2:0:0:0: [sda] 209715200 512-byte logical blocks: (107 GB/100 GiB)
2) To proceed with the partition resize, we will use: sudo fdisk /dev/sda
type: p this will show both partitions /dev/sda1 and /dev/sda2 which are basically partitions 1 and 2
type: d then 2 (to delete partition 2)
type: n then p, 2 (to recreate partition 2) you can accept the default values
type: w (to save the new partition)
type: q (to exit fdisk)
sudo reboot (to reboot the VM so the partition is updated)
3) To finalize the resize, after the reboot, execute the command:
resize2fs /dev/sda2
4) Use the command: df -h to verify its size:
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 98G 1.2G 92G 2% /
For CoreOS (Stable):
No extra steps are necessary, simply deallocating the VM, changing the size on the portal and starting the VM backup will work. CoreOS has a few extra partitions and the extra space will be added to the root partition (usually /dev/sda9).
Comments
- Anonymous
June 14, 2019
Hi Marco, That's really good blog on how to resize OS disk for Linux. Just would like to know whether deleting the partition (sda2) will cause the loss of existing configuration of OS?Thnx- Anonymous
June 17, 2019
Hi Ashu2019,This has been created a while ago, I am not sure today, it shouldn't be changed, as long as you complete the steps you will not lose anything. We always recommend making a copy of the original VHD or a backup of the VM before doing any changes, but the important part is to remember to not reboot before you complete the steps of recreating the partition.I am not on the Azure Linux team anymore too.Thank you,-Marco
- Anonymous