Local storage is temporary or ephemeral, but provides better performance compared to EBS storage. Local storage is ideal for testing and development where you do not need to keep data. Local storage uses SSD or HDD media.
Although local storage is used for the data disk, the root disk uses 350 GB EBS. A minimal charge occurs at the time you launch any instance that uses a root disk.
Local storage leads to data loss in the following node events: shutdown (init 0), node hang, machine check (hardware fault such as a double bit memory error), stopping the instance through the Amazon EC2 Console, or terminating an instance. Data loss does not occur with certain node events, such as a reboot (init 6) or node panic (sometimes referred to as an "oops event"). An "oops event" causes a memory dump and then the node is rebooted.