Your disk is probably full.
The 160 GB number refers to instance storage which is only enabled if you explicitly enable it. The reason why its not enabled by default is that its not persistent. Since this storage is attached to the host, you will loose anything contained in it if you stop your instance or the host fails for any reason.
The storage you are using is an EBS volume. Which is AWS equivalent to a SAN volume. By default, most AMI's create this volume at around 8-10 GB. You can increase its size up to 1TB per volume.
To rectify your current situation, you will need some downtime. You can either do an import into a new instance that is configured with more space. Otherwise, you can snapshot your current volume and use that snapshot to create a new larger volume. You will need to resize the partition to make use of all the space.