I mount a device mount /dev/xvdf /mnt/mongo and verify the mount using df-h: Filesystem Size Used Avail Use% Mounted on /dev/xvda1 7.9G 955M 6.9G 12% / tmpfs 299M 44K 299M 1% /dev/shm /dev/xvdf 20G 589M 19G 4% /mnt/mongo But now I'm trying to figure out how to make it auto mount on boot. I understand I need to add a new entry to /etc/fstab, so I perform: $ sed -i '$ a\/dev/xvdf /mnt/mongo xfs defaults 1 1' /etc/fstab But, after reboot, it seems that the auto mount didn't work. The device didn't appear in the df -h list. Should I not use the sed to add the entry? Is the entry I entered incorrect?