Resizing VMs in Proxmox

Today I wondered how the resizing of a VM works, when I increase the size of the logical volume of a VM. I typically do this using Proxmox and reboot the machine which automatically resizes the disk.

I wondered how I could do the same without rebooting. After increasing the size of the block device in Proxmox using the UI and extend disk I get the following view:

sda       8:0    0   64G  0 disk 
├─sda1    8:1    0 31.9G  0 part /
├─sda14   8:14   0    3M  0 part 
└─sda15   8:15   0  124M  0 part /boot/efi

So I do have 32GB in disk 1 but could increase to 64GB.

To do this, I need:

sudo growpart /dev/sda 1

to extend the partition to the 64G. After which I get:

sda       8:0    0   64G  0 disk 
├─sda1    8:1    0 63.9G  0 part /
├─sda14   8:14   0    3M  0 part 
└─sda15   8:15   0  124M  0 part /boot/efi

Yet, in df -h the new amount is not visible. For this, I also need to increase the file system size of the ext4 inside the partition

sudo resize2fs /dev/sda1

Now df -h is empty again, and everything works as expected.

Conclusion

I did not know that you have to do this for the Block, the partition and the filesystem.

I tried to use resize2fs directly, which fails, as the partition is not resized yet. I always thought that the reason for this is that the sda14 and sda15 are directly behind the sda1 and we would have to move these as well (which is much more complicated). However, using fdisk -l /dev/sda I can see that the sda1 partition is actually at the end of the blockdevice.

Now I also know how to increase the filesystem without rebooting and letting cloud-init do its things.