Adventures in NoSQL, part 2

In Part 1 of this blog series, "Adventures in NoSQL", I deployed a single instance of MongoDB and used Python's tweetstream module to fill a collection with a data feed from Twitter.

In the real world you wouldn't ever use a single instance of MongoDB (or twitter data :-) ) as there is no redundancy if an instance fails, all your data is gone or you need to take some time to restore it from a backup.

However, we can harness the power of a private Eucalyptus IaaS Cloud to use as our infrastructure, this means we can quickly scale out resources using direct EC2 API calls, the euca2ools command line utilities or the Eucalyptus Web interface.

In this post, I'll explore using Replication to spread your data across multiple MongoDB servers for redundancy.

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Backing up a Eucalyptus Cloud Controller

When you first start using Eucalyptus, you are concerned with the intricacies of building images, configuring virtual instances and using all the variety of API features and tools that Eucalyptus offers.

However, when Eucalyptus becomes a tool your business relies on you need to consider making sure you can recover the system from a catastrophic failure. In the enterprise this usually means making adequate backups and being able to restore the whole system from those backups using an automated procedure perhaps with tools such as Ansible, Puppet and Chef or via a documented manual restore procedure. more ...



This last weekend I was over at FOSDEM 2013, where 5,000 geeks descended onto the ULB university in Brussels, Belgium for a huge free and open source software conference. more ...

Adventures in NoSQL, part 1

You've deployed and setup a private Cloud platform but now what? You need an application!

I've been experimenting with a number of technologies to generate workloads and give some demos to prospective Eucalyptus customers. A NoSQL database seems like a great use-case to demo as the technology benefits from being designed for scale-out workloads and this happens to be exactly what an IaaS Cloud does best.

There are an abundance of NoSQL implementations (Cassandra, MongoDB, Couchbase, Neo4j...), written in different programming languages and with slightly different takes on which two parts of the CAP theorem they choose to implement and which method they will use to store and display data.

For this post I'm going to be using MongoDB, which is in the "CP" camp, it handles Consistency and Partition Tolerance whilst forgoing Availability (Every request may not see a response), although MongoDB still provides some great availability options.

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A Keepalived VIP for Eucalyptus Node Controllers

In a Eucalyptus HA configuration there are two Cluster Controllers's (CC) which are in an active-passive state. One is in "ENABLED" mode and one is "DISABLED" mode. If a failure occurs, the active CC services moves to the secondary CC system.

If you combine this with Eucalyptus MANAGED or MANAGED-NOVLAN networking configuration with a private back-end network your Node Controllers (NC) will require a default gateway for access to external networks and to the Walrus service to download Eucalyptus Machine Images.

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