A group of resources that contains a CC, an SC and,
optionally, a VMware Broker.
An availability zone for AWS denotes a large subset of their
cloud environment. Eucalyptus refines this definition to denote a
subset of the cloud that shares a local area network. Each
availability zone has its own cluster controller and storage
A storage container that accepts objects via PUT and GET
A virtual machine image splits the image into multiple image
parts to facilitate ease of uploading. It also generates an XML
manifest file containing metadata referencing the image, including
image parts and kernel, which is used to assemble instances of the
The Cloud Controller (CLC) is the entry-point into the cloud
for administrators, developers, project managers, and end-users. The
CLC queries the node managers [SM1] for information about resources,
makes high-level scheduling decisions, and makes requests to the
Cluster Controllers (CCs). As the interface to the management
platform, the CLC is responsible for exposing and managing the
underlying virtualized resources (servers, network, and storage).
You can access the CLC through Amazon’s Elastic Compute Cloud (EC2)
and through a web-based Eucalyptus Administrator Console.
The Cluster Controller (CC) generally executes on a machine
that has network connectivity to both the machines running the Node
Controller (NC) and to the machine running the CLC. CCs gather
information about a set of node machines and schedules virtual
machine (VM) execution on specific nodes. The CC also manages the
virtual machine networks and participates in the enforcement of
SLAs[SM3] as directed by the CLC. All nodes associated with a single
CC must be in the same broadcast domain (Ethernet).
A ramdisk contains drivers that direct the kernel to launch
appropriate system files when instantiating a virtual
The Node Controller (NC) executes on any machine that hosts VM
instances. The NC controls VM activities, including the execution,
inspection, and termination of VM instances. It also fetches and
maintains a local cache of instance images, and it queries and
controls the system software (host OS and the hypervisor) in
response to queries and control requests from the CC. The NC is also
responsible for the management of the virtual network
The Storage Controller (SC) provides functionality similar to
the  Amazon Elastic Block Storage (EBS) and is capable of
interfacing with various storage systems (NFS, iSCSI, SAN devices,
etc.). Elastic block storage exports storage volumes that can be
attached by a VM and mounted or accessed as a raw block device. EBS
volumes persist past VM termination and are commonly used to store
persistent data. An EBS volume cannot be shared between VMs and can
only be accessed within the same availability zone in which the VM
is running. Users can create snapshots from EBS volumes. Snapshots
are stored in Walrus and made available across availability zones.
Eucalyptus with SAN support lets you use your enterprise-grade SAN
devices to host EBS storage within a Eucalyptus cloud.
VMware Broker (Broker or VB) is an optional Eucalyptus
component activated only in versions of Eucalyptus with VMware
support. VMware Broker enables Eucalyptus to deploy VMs on VMware
infrastructure elements and mediates all interactions between the
Cluster Controller (CC) and VMware hypervisors (ESX/ESXi) either
directly or through VMware vCenter.
Walrus allows users to store persistent data, organized as
buckets and objects. You can use Walrus to create, delete, and list
buckets, or to put, get, and delete objects, or to set access
control policies. Walrus is interface compatible with Amazon’s
Simple Storage Service (S3), providing a mechanism for storing and
accessing virtual machine images and user data. Note that Walrus
access is global to the entire Eucalyptus cloud. This means that it
can be accessed by end-users, whether the user is running a client
from outside the cloud or from a virtual machine instance running
inside the cloud.