Exercise - Resize a VM disk


Let's say you underestimated how large some of the uploaded files would be and that your upload disk is running out of space. You decide to double the space from 64 GB to 128 GB.

Here, you'll practice the process you learned about in the previous units.

Resize the data disk

To resize a disk, you need the ID or name of the disk. In this case, you already know the name, uploadDataDisk1. But in case you didn't remember that, or it was created by someone else, you can run az disk list to find the name.

  1. Run the az disk list command to print the list of the managed disks in the resource group. This list might include other disks if you have multiple VMs in the same resource group.

    az disk list \
      --query '[*].{Name:name,Gb:diskSizeGb,Tier:sku.tier}' \
      --output table

    You see the disk named uploadDataDisk1.

    Name                                                        Gb
    ----------------------------------------------------------  ----
    support-web-vm01_OsDisk_1_141859cb21d64b85b9db3f70f0f5e851  30
    uploadDataDisk1                                             64
  2. Run the following az vm deallocate command to stop and de-allocate your VM. This does not delete your VM, but puts it in a state where you can modify the virtual disks.

    az vm deallocate --name support-web-vm01
  3. Run the az disk update command to resize the disk to 128 GB.

    az disk update --name uploadDataDisk1 --size-gb 128
  4. Run the az vm start command to restart the VM.

    az vm start --name support-web-vm01

    But we aren't finished yet. The operating system on the VM cannot use the extra space yet. We'll do this in the next section.

Expand the disk partition

The final step is to tell the OS about the available space. Just like the partitioning and format steps you did earlier, this process is identical to the one you'd follow to expand a physical on-premises disk.

  1. Although you can reserve a fixed public IP address for your VM, by default your VM receives a new public IP address when it is de-allocated and restarted. Run the following az vm show command to update your Bash variable with your VM's new public IP address.

    ipaddress=$(az vm show --name support-web-vm01 -d --query [publicIps] -o tsv)
  2. As you did earlier, run lsblk on your VM over SSH to understand its current state.

    ssh azureuser@$ipaddress lsblk

    You can see that disk sdc/sdc1 still has a size of 64 GB.

    sdb      8:16   0   14G  0 disk 
    └─sdb1   8:17   0   14G  0 part /mnt
    sdc      8:32   0  128G  0 disk 
    └─sdc1   8:33   0   64G  0 part /uploads
    sda      8:0    0   30G  0 disk 
    └─sda1   8:1    0   30G  0 part /
  3. Similar to what you did previously to initialize your disk, run the following az vm extension set command to tell the OS on the VM about the newly available space by executing a pre-made Bash script we create to help you along.

    az vm extension set \
      --vm-name support-web-vm01 \
      --name customScript \
      --publisher Microsoft.Azure.Extensions \
      --settings '{"fileUris":["https://raw.githubusercontent.com/MicrosoftDocs/mslearn-add-and-size-disks-in-azure-virtual-machines/master/resize-data-disk.sh"]}' \
      --protected-settings '{"commandToExecute": "./resize-data-disk.sh"}'

    While the command runs, you can examine the Bash script from a separate browser tab if you'd like.

    To summarize, the script:

    • Unmounts the disk /dev/sdc1.
    • Resizes partition 1 to be 128 GB.
    • Verifies partition consistency.
    • Resizes the filesystem.
    • Remounts the drive /dev/sdc1 back to the mount point /uploads.
  4. To verify the configuration, run lsblk on your VM over SSH a second time.

    ssh azureuser@$ipaddress lsblk

    This time, you see that disk sdc/sdc1 is expanded to accommodate the increased size of your disk.

    sdb      8:16   0    14G  0 disk 
    └─sdb1   8:17   0    14G  0 part /mnt
    sdc      8:32   0   128G  0 disk 
    └─sdc1   8:33   0 119.2G  0 part /uploads
    sda      8:0    0    30G  0 disk 
    └─sda1   8:1    0    30G  0 part /
  5. As a final verification step, run the operating system's df utility on your VM over SSH to prove that the OS can see it correctly.

    ssh azureuser@$ipaddress df -h

    You see that the drive's size is 128 GB.

    Filesystem      Size  Used Avail Use% Mounted on
    udev            3.4G     0  3.4G   0% /dev
    tmpfs           697M  8.6M  689M   2% /run
    /dev/sda1        30G  1.4G   28G   5% /
    tmpfs           3.5G     0  3.5G   0% /dev/shm
    tmpfs           5.0M     0  5.0M   0% /run/lock
    tmpfs           3.5G     0  3.5G   0% /sys/fs/cgroup
    /dev/sdb1        14G   35M   13G   1% /mnt
    /dev/sdc1       118G   60M  112G   1% /uploads
    tmpfs           697M     0  697M   0% /run/user/1000