Confused about df and lsblk commands showing different information?

Question

$ lsblk
NAME  MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
xvda1 202:1    0   20G  0 disk /
xvda3 202:3    0  896M  0 disk [SWAP]
$ df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/xvda1      7.9G  2.1G  5.8G  27% /
tmpfs           829M     0  829M   0% /dev/shm

Why does lsblk telling me that I have 20G disk space on xvda1, while df command is telling me I only have 8G disk space?

Answer 1

I had this same issue. I used sudo resize2fs /dev/xvda1 to make the rest of the disk space available.