Are you unsure whether your mass storage works properly? Do you suspect it's faulty somewhere?
Verify it with a nifty tool, included in most Linux distros and in macOS if you install the ext2fs tools:
sudo badblocks -swv -t random -b 4096 -c 2048 <DEVICE>
It will perform a read-write test of your mass storage device, and tell you what's wrong.
WARNING: everything will be deleted during the test! Make sure you've already backupped your data!