How to increase Ubuntu/Debian OS storage capacity after creation the VM / Template on Proxmox.

 I have my own local Proxmox virtualization server, and I have created few windows, ubuntu, debian, centos VM's with Template. But, I have created the template of the VM with low storage capacity now I wants to increase, how?

Let me share it here, if I need it later I can come and see this guides.

Let's see first my current storage: 32GB

I want to increase more 500GB. 

Select your VM > Hardware > Hard Disk > Disk Action > Resize

I have given 500GB input, you give yours's.

See the changes:

My first step is done on proxmox, now I need to log into the Ubunutu/Debian VM by using SSH or by Proxmox console (you can't copy paste the command - need to type; for long command I don't use this, I prefer SSH).

Proxmox Console:

And PuTTY - SSH

Check if the new space is visible:

lsblk

Ensure the virtual disk (e.g., /dev/sda) reflects the increased size.

If the main partition doesn't use all available space: Launch the partition tool

sudo cfdisk /dev/sda

Select the main partition (e.g., /dev/sda3 for LVM).

Select > Resize

Choose your desired number and press Enter.

Now change the /dev/sda3 storage has increased.

And now need to finalize the resized storage capacity by write to it. Select > Write

Type: Yes and Press Enter

Let's see if it works, Type:

lsblk

Yes, it worked in my side.