had to resize my EBS on AWS. i followed amazon's instructions which basically had me mount the EBS/HD on a second machine (as a secondary disk) and use 'gdisk' to resize the partition. Then they say to mount the EBS/HD back onto the original machine (restart it) and do 'resize2fs'.
However, after launching the original instance, 'df' showed the "available" and "use %" as being aware of the size I added using gdisk (on the other machine). I did not have to use resize2fs at all.
So, my question is: how did my system automatically resize the filesystem? As far as I'm aware, all i did was resize the partition, but not the filesystem? Amazon's documentation makes it seem like this is 2 different things. Do I still need to do the resize2fs? Will I run into complications later on if i don't? I'm afraid i'm running in some purgatory state even though everything seems fine (and i can save new files whereas previously the HD was 100% full before this).
The format is ext4 (GPT with protective MBR) if that helps.