CORRECT TEXT
Create a 512M partition, make it as ext4 file system, mounted automatically under /mnt/data and which take effect automatically at boot-start.
Answer: see explanation below.
Explanation
# fdisk /dev/vda
n
+512M
w
# partprobe /dev/vda
# mkfs -t ext4 /dev/vda5
# mkdir -p /data
# vim /etc/fstab
/dev/vda5 /data ext4 defaults 0 0
# mount -a