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Sunday, December 11, 2011

Conception and validation of Hadoop BigData stack: putting the record straight.

With more and more people jumping on bandwagon of big data it is very settling to see that Hadoop is gaining momentum by a day.

Even most fascinating is too see how the idea of putting together a bunch of service components on top of Hadoop proper is getting more and more momentum. IT and software development professionals are getting better understanding about benefits that a flexible set of loosely coupled yet compatible components provides when one needs to customize data processing solution at scale.

The biggest problem for most businesses trying to add Hadoop infrastructure into their existing IT is a lack of knowledge, professional support, and/or clear understanding of what's out there on the market to help you. Essentially, Hadoop exists in one incarnation - this is the open-source project under the umbrella of Apache Software Foundation (ASF). This is where all the innovations in Hadoop are coming from. And essentially this is a source of profit for a few commercial offerings today.

What's wrong with the picture, you might ask? Well, the main issue with most of these "commercial offerings" are mostly two folds. They are either immature and based on an sometimes unfinished nor unreleased Hadoop code, or provide no significant value add compare to Hadoop proper available in source form from hadoop.apache.org. And no matter if any of above (or both of them together) apply to a commercial solution based on Hadoop, you can be sure of one thing: these solutions will cost you literally tons of money - as much as  $1k/node/year in some cases - for what is essentially available for free.

"What about neat packages I can get from a commercial provider and perhaps some training too?" one might ask. Well, yeah if you are willing to pay top bucks per node for say like this  to get fixed or learn how to install packages on a virtual machine - go ahead by all means.

However, keep in mind that you always can get a set of packages for Hadoop produced by another open source project called Bigtop, hosted by Apache. What essentially you get are packages for your Linux distro, which can be easily installed on your cluster's nodes. A great benefit is that you can easily trim your Hadoop stack to only include what you need: Hadoop + Hive, or perhaps Hadoop + HBase (which will automatically pick up Zookeper for you).

At any rate, the best part of the story isn't a set of packages that can be installed: after all this is what packages are usually being created for, right? The problem with the packages or other forms of component distribution is that you don't know in advance if A-package will nicely work with B-package v.1.2 unless some has tested this assumption before. Even then, testing environment  might be significantly different from your production environment and then all bets are off. Unless - again - you're willing to pay through your nose to someone who's willing to get it for you. And that's where true miracle of something like BigTop is coming for a rescue.

Before I'll explain more, I wanna step back a bit and take a look at some recent history. A couple of years ago Yahoo's Hadoop development team had to address an issue of putting together working and well-validated Hadoop stack including a number of components developed by different engineering organizations with their own development schedule and integration criteria. The main integration point of all of the pieces was the operations team which was in charge of big number of cluster deployments, provisioning and support. Without their own QA staff they were oftentimes at mercy of assumed code or configuration quality coming from all the corners of the company. Yet worst, even with a chance of the high quality of all these components there were no guarantees that they will work together as expected once put together on the cluster. And indeed, integration problems were many.

That's were a small team of engineers including yours truly put together a prototype of a system called FIT (Final Integration Testing). The system essentially allowed you to pick up a packaged component you want to validate against your cluster environment and perform the deployment, configuration, and testing with integration scenarios provided by either component's owner or your own team.

The approach was so effective that the project was continued and funded further in the form of HIT (Hadoop Integration Testing). At which point two of us have left for what seemed like a greener pasture back then :(

We thought the idea was real promising so we have continued on the path of developing a less custom and more adoptable technology based on open standards such as Maven and Groovy. Here you can find slides from the talk we gave at eBay about a year ago. The presentation is putting the concept of Hadoop data stack in open writing for the time, as well as stacks customization and validation technology. When this presentation were given we already had well working mechanism of creating, deploying, and validating both packaged and non-packaged Hadoop components.

BigTop - open-sourced for the second time just a few months and based on our project above - has added up a packaging creation layer on top of the stack validation product. This, of course, makes your life even easier. And even more so with a number of Puppet recipes allowing you to deploy and configure your cluster in highly efficient and automatic manner. I encourage you to check it out.

BigTop has been successfully used for validating release of Apache Hadoop 0.20.205 which has become a foundation of coming Hadoop 1.0.0 Another release of Hadoop - 0.22 - was using BigTop for release candidates validation and so on.

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