your computer's drive itself. The easiest solution would be to get a new drive to replace it. You can get one from Apple or from Amazon: Apple: G-Technology 2TB G-DRIVE mobile USB 3.0/USB-C Portable Hard Drive $95 https://www.apple.com/shop/product/HL612ZM/A/q-technoloqv-2tb-q-drive- mobile-usb-30-portable