@Fábio Leal Viana Bones
Unless you have a data disk attached to your vm /dev/sdc1 is likely the temporary disk for your VM. Since this is a physical drive attached to your VM, you will not be able to increase its size. Also any data on this volume should be considered temporary and can be lost at anytime due to hardware issue or if the VM is stopped. I recommend moving any persistent data off this disk by creating and attaching a data disk to your VM.
Hope this helps. Let us know if you have further questions or issues.
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