A drum's whole is a barrel made of green alloy or tube carrying an electrical charge that is static from the cartridge that contains toner in order to remove the particles of toner. It also connects to the printer's page as the printer moves. So, you can see that the whole drum is close to the ink cartridge, or even is connected to it. Additionally, You should encounter problems related to this drum by following the methods mentioned here Why is my Brother Printer offline windows 10