Giuseppe Paternò

IT Architect and highly skilled in IT Security, he has a broad background in the Open Source world. He has worked as a consultant for companies such as Red Hat, Canonical, Sun and IBM, in addition to being Managing Director of the Swiss multinational GARL. He also deals with technologies about CloudStack and OpenStack, for which he has written a reference manual.

Previous article: OpenStack Components

Horizon – Dashboard

Horizon provides a modular web-based user interface for all the OpenStack services. With this web GUI, you can perform most operations on your cloud like launching an instance, assigning IP addresses and setting access controls.

openstack horizon dashboard

Read more OpenStack - Horizon and Keystone

Previous article: OpenStack Introduction

OpenStack is a collection of open source technologies delivering a massively scalable cloud operating system.

OpenStack cloud operating system controls large pools of compute, storage and networking resources throughout a datacenter, all managed through a dashboard that gives administrators control while empowering their users to provision resources through a web interface.

We can think of it as software to power our own Infrastructure as a Service (IaaS) offering, like the one behind Amazon Web Services.

Read more OpenStack - Components

I’ve been sitting in front of many European IT Managers and CTOs and when they want to hear from me about OpenStack or Cloud, most of the times they mean something different: customers want a VMware replacement for virtualization. The most audacious ones are willing to have a nice web interface to access their virtual machines and that’s it.

Cloud sounds like yet another marketing buzzword, it can mean just about anything or nothing at all. We are not discussing here what is the reason of walking away from VMWare, but the idea of the equation “Cloud=Virtualization” is pretty spread across all the customers. This is actually what some vendors tried to let you think of cloud.

While Cloud implies a virtualized environment, virtualization is not a cloud. Let me define Cloud using the NIST definition: “Cloud computing is a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (ex: networks, servers, storage, applications and services) that can be rapidly provisioned and released with minimal management effort”.

Read more OpenStack - Cloud: a planet to discover

Previous article: OpenStack: a planet to discover

The great advantage of OpenStack is that the end customer can choose whether to use the reference implementations for each project or a vendor-specific implementation for each one. The promise of OpenStack is the interoperability amongst different components from different vendors or open source projects, giving the customer the choice to find out what is the best solution for their own needs.

OpenStack could bring the following benefits to you:

Read more OpenStack - Introduction to OpenStack

OpenStack was made from the ground up to scale to thousands of nodes and span different datacenters and geographical regions. For this reason, Openstack clouds can be divided in three main hierarchical zones: Regions, Availability Zones and Host Aggregates.

openstack regions

Each Region has its own full Openstack deployment, including its own API endpoints, networks and compute resources. Different Regions share one set of Keystone and Horizon services, to provide access control and a Web interface.

Availability Zone
Inside a Region, compute nodes can be logically grouped into Availability Zones (AZ): when launching a new VM instance we can specify the AZ we want it instantiated in, or even a specific node inside an AZ to run the VM instance.

Host Aggregates
Besides AZs, compute nodes can also be logically grouped into Host Aggregates.
Host Aggregates have meta-data to tag groups of compute nodes, e.g. all nodes with an SSD disk can belong to one Host Aggregate, while another Host Aggregate may contain all nodes with 10 GB NICs.

One compute node can be put into both an Host Aggregate and an Availability Zone at the same time, as they do not conflict. Moreover, one compute node can belong to more than one Host Aggregate. Host Aggregates are visible only to the admin and can also be used to mix hypervisors in the same AZ, for example to save license costs: some vendors provide free guests for their hypervisors.

OpenStack Compute cells allow you to run the cloud in a distributed fashion. Hosts in a cloud are partitioned into groups called cells. Cells are configured in a tree. The top-level cell ("API cell") has a host that runs the nova-api service, but no nova-compute services.

This allows for a single API server being used to control access to multiple cloud installations. Introducing a second level of scheduling (the cell selection), in addition to the regular nova-scheduler selection of hosts, provides greater flexibility to control where virtual machines are run.

Unlike having a single API endpoint, regions have a separate API endpoint per installation, allowing for a more discrete separation. Users wanting to run instances across sites have to explicitly select a region. However, the additional complexity of running a new service is not required.

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