Amazon EC2 with or without EBS? [closed]

Question

Still reading up on AWS. Amazon Large Instances comes with 850GB local storage. However, i read in case of failover and we want to power up another instance, we can just mount a EBS volume on it and start running right? That will mean that we have to configure and store it on a EBS volume to enjoy this capability. Does that mean that with local storage, say if data are saved in local, we will not able to do it ? EBS is charged separately, the large local storage of 850GB might not be that advantageous ? Is EBS used normally for Webserver data or primary for MySQL for persistent data?

Anyone who has experience with AWS can have good inside on this? That will mean that most of the instances i pay for have to buy EBS to enjoy the switch over capability?

Quicktempered

Answer 1

I recommend you start out using EBS entirely. That means running an EBS boot AMI, and putting your data (web, database, etc) on a separate EBS volume (recommended) or even the EBS root volume. Here's an article I wrote that describes more details about why I feel this way for beginners:

http://alestic.com/2012/01/ec2-ebs-boot-recommended

The listed 850GB local storage is ephemeral, which means that it is at risk of being lost forever if you stop your instance, terminate your instance, or if the instance fails. It might be useful to use for things like a large /tmp but I recommend against using ephemeral storage for anything valuable.

Note also that the 850 GB is not in a single partition, is not all attached to the instance by default, and is not all formatted with a file system by default.

Blen

EBS is ephemeral too. It's just a RAID-1. – Indole

@Indole In the AWS EC2 framework, "ephemeral" is a technical term with a specific meaning, and EBS volumes are not ephemeral. Ephemeral refers to local "instance-store" disks that disappear when an instance fails or is terminated. EBS volumes are preserved if an instance fails or is stopped. You can even flip a switch so that EBS volumes are preserved if an instance is terminated. – Blen