Problem scenario
You have added a partition to Linux. When you type "df -h" you do not see evidence that it is available. You tried the "sudo lsblk" command, but you do not see the device. The "fdisk -l" command does show the new device and the size that is available. The command ll /dev/sd* does not show your new device.
When you run "fdisk /dev/sdaX", you get this: "fdisk: cannot open /dev/sdaX: No such file or directory"
How do you make it available?
Solution
Reboot the server.