Expand Azure Virtual Machine Scale set (VMSS) data disks

Question

I have a VM with 2 virtual machine scale set. There's a requirement to expand the datadisk. I have successfully expanded the VM's datadisk (attached disk). After which I am trying to expand the size of scale set data disks but with failure.

This is what I have done to expand the VM attached disk:

az disk update --resource-group e4s --name e4s-vm-0_disk2_a3d99285cfbc4f0987c8a9c8e4c1f7ef --size-gb 130

ssh to the instance and executed:

sudo mdadm --assemble --update=devicesize /dev/md0 /dev/sdc
sudo mount /dev/md0 /mnt/data
sudo xfs_growfs /mnt/data

After which df -h had shown the expanded size correctly.

For the VMSS, this is what I have done:

az vmss update -n e4s-ss -g e4s --set virtualMachineProfile.storageProfile.dataDisks[0].diskSizeGb=130

Checked the scale set model:

az disk update --resource-group e4s -n e4s-vm-0_disk2_a3d99285cfbc4f0987c8a9c8e4c1f8ef --size-gb 130

[
  {
    "caching": "None",
    "createOption": "empty",
    "diskSizeGb": 130,
    "lun": 0,
    "managedDisk": {
      "storageAccountType": "Premium_LRS"
    },
    "name": null
  }
]

In portal also it's showing the size as 130 Updated the sc

Since the upgrade policy is manual so updated it:

az vmss update-instances -n e4s-ss -g e4s --instance-ids 1
az vmss update-instances -n e4s-ss -g e4s --instance-ids 2

After ssh connection to one of the vmss executed the same commands which were executed after expanding the VM disk. But the newly expanded size is not being displayed.

Answer 1

After doing the first step: az vmss update -n e4s-ss -g e4s --set virtualMachineProfile.storageProfile.dataDisks[0].diskSizeGb=130

Did go back to the Azure Portal, click on instances, select the instances and click on upgrade??

I did that and it work for me.

Answer 2

Not sure about the mdadm never used used it but have used article below to successfully resize a data disk.

https://docs.microsoft.com/en-us/azure/virtual-machines/linux/expand-disks#expand-a-disk-partition-and-filesystem

Try it and see if it works for you.

Answer 3

Whatever procedure I have followed is correct. Instead of stopping the vmss they have to be deallocated and started again.