Rob Hirschfeld's Blog

Analyze This! Big Data | Apache Hadoop | Dell | Cloudera | Crowbar February 20, 2012

This article about Target using buying patterns to expose a teen was pregnant before she told her parents puts big data analysis into everyday terms better than the following 555 words (of course, I recommend that you read both).

Recently, I had the pleasure of being one of our team presenting Dell’s BIG DATA story at an internal conference. From the questions and buzz, it’s clear that the big data is big news this year. My team is at the center of that storm because we are responsible for the Dell | Cloudera Apache™ Hadoop™ solution. The solution is significant because we’ve integrated many pieces necessary to build and sustain a Hadoop cluster: that includes Dell servers, the Cloudera Hadoop distribution, the Crowbar framework and Services to make it useful.

Big Data Analytics spins data straws into information gold.

Before I jump into technical details, it’s worth stating the big data analytics value proposition. The problem is that we are awash in a tsunami of data: we’ve grown beyond the neat rows and columns of application databases, data today include source like website click logs and emails to call records and cash register receipts to including social media tweets and posts. While much of the data is unstructured noise, there is also incredibility valuable information.  (video of my Hadoop “escalator pitch”)

Value is not just hidden inside the bulk data; it lies in correlations between sets of the data.

The big data analytics value proposition is to provide a system to hold a lot of loosely structured information (thus “big data”) and then sift and correlate the information (thus “analytics”). The result is a technology that helps us make data driven decisions. In many applications, the analysis is fed directly back into applications so they can alter behavior in near real-time. For example, an online retail store could offer you purple bunny slippers as you browse for crowbars in the hardware section knowing that you’re reading this post. That is the type of correlations on disparate data that I’m talking about.

This is really two problems: storing a lot of data and then computing over it.

Hadoop, the leading open source big data analytics project, is a suite of applications that implement and extend two core capabilities: a distributed file system (HDFS) and the map-reduce (M-R) algorithm. My point is not to define Hadoop (others have done better and here); instead, I want to highlight that it’s a combination big data analysis is a merger of storage and compute. When learning about any big data analysis solution, you cannot decouple how the data is stored from how the data is analyzed – storage and compute are fundamentally linked.

For that reason, the architecture of a Hadoop cluster is different than either a traditional database or compute cluster. The IO and the resiliency patterns are different. Since Hadoop is a distributed system, hardware redundancy is less important and eliminating IO bottlenecks is paramount. For this reason, our Hadoop clusters use a lot of local, non-RAID drives with a target of delivering a 1:1 CPU core to spindle ratio (ratios are tuned based on planned loads).

Imagine that you are looking for correlations in web click data. To do that analysis, Hadoop need to spend a lot of time cracking open log files, sifting for specific data and then reporting back its results. That process involves thousands of jobs each doing disk IO, CPU & RAM workload and then network transfer; consequently, contention between network and disk demands reduces performance.

Wow… that’s a lot of description and just scratching the surface of Big Data Analytics. I’ll going to have to add the technical details about the Dell solution architecture (Hardware) and software components (Cloudera & Crowbar) in another post.