Wednesday 27 May 2015

Understanding AWS Storage Solutions: Ephemeral, EBS and S3 Storage

Amazon Web Services provides two main storage solutions - S3 and Ephemeral Storage that I have outlined below:

Ephemeral Storage: This is a non-persisent block level storage solution that Amazon offers free of charge. When allocated if a VM instance is turned off (not restarted) all data on the storage is lost.

Ephemeral Storage is bundled with EC2 instances and can be used in some of the following scenerios:

- Used as a buffer, caches for applications
- Replication data for load-balanced virtual machines

The storage does not have any access speed or availaiblity garuntees and should therefore not be used for anyting mission critical - as man different AWS users typically share a server within the Ephemeral Storage platform.

Amazon Simply Storage (S3): This is a persistent storage solution which is accessable via a web API over HTTP and HTTPS.

Data is held within "buckets" similar to Azure's "containers" and can be of unlimited size - although object sizes are limited to 5TB.

You are priced on the amount of storage used and the outgoing bandwdith - although not the incoming bandwidth.

There are two types of storage types:

- Standard storage: That provides very high data redundancy via replicating your data between availability zones - providing quote "99.999999999%" durability.

- Reduced Redundancy Storage: Provides reduced redundancy / durability for storage at 99.99% - although is cheaper than standard storage.

Elastic Block Storage (EBS): Is part of EC2 and is not accessable via any web API's - it is used as a persistent storage type for EC2 instances.

For example the system drive within a newly provisioned virtual machine will utilize EBS - although additional EBS volumes can be added, removed and moved between different virtual machines and availability zones.

You are able to take snapshots of EBS - that are stored within S3 storage, although not directly accessable to us.


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