I think the key word here is as, actually.  The word as lets you know that it's a simile; the word on is just the preposition in the phrase "feast on [something]".

It means the same thing as if these words were inserted:


  We feasted [on the food we had] that evening as [we would] on nectar and ambrosia [...]


Meaning of 'on' in "We feasted that evening as 'on' nectar and ambrosia"
I had an EBS volume of 30GB that was mounted as the rootfs for a ubuntu server. Due to space concerns I had to increase the size of the volume to 50. So I carried out the following steps:


  
  Take a snapshot of the EBS volume.
  Created a new EBS volume of 50GB.
  Restored the snapshot to the new volume.
  Power off my EC2 instance.
  Unmounted my old volume and mounted my new volume.
  


Every thing works fine. But when I do a df -h I get this:

Filesystem Size Used Avail Use% Mounted on
rootfs 30G 27G 1.1G 97% /
devtmpfs 1.9G 112K 1.9G 1% /dev
tmpfs 1.9G 0 1.9G 0% /dev/shm
/dev/xvde1 30G 27G 1.1G 97% /


And when I do fdisk -l I get this:

Disk /dev/xvde1: 53.7 GB, 53687091200 bytes.


Could some one help me with this?
