Eucalyptus Architecture : From My Point of View

About this article

This article focuses on understanding the architecture of Eucalyptus private cloud platform, community edition from the author point of view.

Introduction

Eucalyptus is an AWS (Amazon Web Services) API compatible private cloud platform. Its architecture is quite simple yet effective. To understand it, let's see it in detail.

As per the official website of Eucalyptus, the architecture has categorized into three levels:

1. User Level
2. Cloud Level
3. Cluster Level
4. Node Level

The architecture has explained in great detail from technical point of view, so there is no point in reinventing the wheel. For me, I will place components and architecture as follows:

• Controller Level
• Storage Level
• Node Level

The Controller level consists of Cloud Controller, Cluster Controller.

The Storage level consists of Walrus, Storage Controller.

The Node level consists Node Controller.

Note: VMWare Broker is not the part of this discussion as it is only available for Eucalyptus Enterprise edition.

In Controller level, you will see the controlling and management components:

1. Cloud Controller [CLC]: It is heart of Eucalyptus. It performs all REST and SOAP based communication with other Eucalyptus as well as external components.

In short, it is main authority without which nothing can be orchestrate between Eucalyptus Cloud Components.

2. Cluster Controller [CC]: It is one which manages networking operations. The instance management between NC and CLC get managed by CC.

In storage level, you will see the Storage related components:

3. Walrus [W] : Amazon Simple Storage Service (S3) based storage which is used to simply put data into it. No rigorous database operations are performed on it.

Simple, create,store and fetch data from Eucalyptus that's all what Walrus is !

4. Storage Controller [SC] : It is similar to EBS (Elastic Block Storage). What am I telling new? We will go in detail by breaking it:

Elastic =  One can be expandable

Block   =  Certain Amount of Storage (in GB,TB, PB & so on)

Storage = The same concept as explained above.

So, the SC is used to:

• Create, delete volume as well as attach & detach to and from instance. 
• Create Snapshots from Volume and reverse. 

In Node Level, it only deals with Compute Part:

5. Node Controller [NC] :  It is known to be compute part. Compute means it provides all things need to run a virtual machine like CPU Cores, Memory, Hard Disk. Same things that we require to run an Operating System under Hypervisors like VMWare, Virtualbox.

That's all about Eucalyptus Architecture !

So basics for Newbs in cloud as follows:

Instance: It is a short form of Virtual Machine Instance similar that we see while running operating system in Virtualbox or VMWare Workstation.

EC2 Instance: Instance which is for temporary purpose i.e.  testing only. On this instance, data will get vanished after its termination i.e. destruction. We can attach volume to this to make new images.[How? We will see later in detail.]

EBS-Based Instance: This instance itself generated the volume when it starts running. So, after shutdown volume state remains attached until we terminate it.

Benefit of this is we can attach extra volume to increase the storage.

Start: To boot up the instance

Stop: To shutdown the instance

Terminate : To destroy the instance along with its data.

Volume: Detachable Storage which we attach to instance same as that External USB Hard Disk or Pen drive which we attach to our computer.

Snapshot: Same as like we take in Virtualbox to save the state of running VM.