Cloudera Engineering Blog · CDH Posts

How Cloudera Ensures HBase Client API Compatibility in CDH

Apache HBase supports three primary client APIs that developers can use to bind applications with HBase: the Java API, the REST API, and the Thrift API. Therefore, as developers build apps against HBase, it’s very important for them to be aware of the compatibility guidelines with respect to CDH.

This blog post will describe the efforts that go into protecting the experience of a developer using the Java API. Through its testing work, Cloudera allows developers to write code and sleep well at night, knowing that their code will remain compatible through supported upgrade paths.

Flexpod Select with Cloudera

Earlier this week, our partners NetApp and Cisco announced the Flexpod Select Family with support for Cloudera’s Distribution including Apache Hadoop (CDH).

We’re looking forward to the expansion of Flexpod Select to include Hadoop, as it provides additional options for customers to consume the benefits of the Cloudera Enterprise platform.

It’s All About You: New Community Forums for Cloudera Customers and Users

This is a great day for technical end-users – developers, admins, analysts, and data scientists alike. Starting now, Cloudera complements its traditional mailing lists with a new, feature-rich community forums intended for users of Cloudera’s Platform for Big Data!  (Login using your existing credentials or click the link to register.)

Although mailing lists have long been a standard for user interaction, and will undoubtedly continue to be, they have flaws. For example, they lack structure or taxonomy, which makes consumption difficult. Search functionality is often less than stellar and users are unable to build reputations that span an appreciable period of time. For these reasons, although they’re easy to create and manage, mailing lists inherently limit access to knowledge and hence limit adoption.

Calling All CDH Users: Submit Your Nomination for the Data Impact Awards

AwardsUsers of CDH, Cloudera’s Big Data platform, are solving big problems and building amazing solutions with Apache Hadoop. We at Cloudera are very proud of our customers’ accomplishments, and it’s time to showcase them. This year we’re thrilled to present the first annual Data Impact Awards, an awards program designed to recognize Hadoop innovators for their achievements in five categories:

Customer Spotlight: Motorola Mobility’s Award-Winning Unified Data Repository

The Data Warehousing Institute (TDWI) runs an annual Best Practices Awards program to recognize organizations for their achievements in business intelligence and data warehousing. A few months ago, I was introduced to Motorola Mobility’s VP of cloud platforms and services, Balaji Thiagarajan. After learning about its interesting Apache Hadoop use case and the success it has delivered, Balaji and I worked together to nominate Motorola Mobility for the TDWI Best Practices Award for Emerging Technologies and Methods. And to my delight, it won!

Chances are, you’ve heard of Motorola Mobility. It released the first commercial portable cell phone back in 1984, later dominated the mobile phone market with the super-thin RAZR, and today a large portion of the massive smartphone market runs on its Android operating system.

How Does Cloudera Manager Work?

At Cloudera, we believe that Cloudera Manager is the best way to install, configure, manage, and monitor your Apache Hadoop stack. Of course, most users prefer not to take our word for it — they want to know how Cloudera Manager works under the covers, first. 

In this post, I’ll explain some of its inner workings. 

The Vocabulary of Cloudera Manager

What a Great Year for Hue Users!

HueWith the recent release of CDH 4.3, which contains Hue 2.3, I’d like to report on the fantastic progress of Hue in the past year.

For those who are unfamiliar with it, Hue is a very popular, end-user focused, fully open source Web UI designed for interaction with Apache Hadoop and its ecosystem components. Founded by Cloudera employees, Hue has been around for quite some time, but only in the last 12 months has it evolved into the great ramp-up and interaction tool it is today. It’s fair to say that Hue is the most popular open source GUI for the Hadoop ecosystem among beginners — as well as a valuable tool for seasoned Hadoop users (and users generally in an enterprise environment) – and it is the only end-user tool that ships with Hadoop distributions today. In fact, Hue is even redistributed and marketed as part of other user-experience and ramp-up-on-Hadoop VMs in the market.

Apache Bigtop: The "Fedora of Hadoop" is Now Built on Hadoop 2.x

BigtopJust in time for Hadoop Summit 2013, the Apache Bigtop team is very pleased to announce the release of Bigtop 0.6.0: The very first release of a fully integrated Big Data management distribution built on the currently most advanced Hadoop 2.x, Hadoop 2.0.5-alpha.

Bigtop, as many of you might already know, is a project aimed at creating a 100% open source and community-driven Big Data management distribution based on Apache Hadoop. (You can learn more about it by reading one of our previous blog posts on Apache Blogs.) Bigtop also plays an important role in CDH, which utilizes its packaging code from Bigtop — Cloudera takes pride in developing open source packaging code and contributing the same back to the community.

Configuring Impala and MapReduce for Multi-tenant Performance

Cloudera Impala has many exciting features, but one of the most impressive is the ability to analyze data in multiple formats, with no ETL needed, in HDFS and Apache HBase. Furthermore, you can use multiple frameworks, such as MapReduce and Impala, to analyze that same data. Consequently, Impala will often run side-by-side with MapReduce on the same physical hardware, with both supporting business-critical workloads. For such multi-tenant clusters, Impala and MapReduce both need to perform well despite potentially conflicting demands for cluster resources.

In this post, we’ll share our experiences configuring Impala and MapReduce for optimal multi-tenant performance. Our goal is to help users understand how to tune their multi-tenant clusters to meet production service level objectives (SLOs), and to contribute to the community some test methods and performance models that can be helpful beyond Cloudera.

Defining Realistic Test Scenarios

CDH 4.3: Now Shipping with More Apache HBase Improvements

As you may know, Apache HBase has a vibrant community and gets a lot of contributions from developers worldwide. The collaborative development effort is so active, in fact, that a new point-release comes out about every six weeks (with the current stable branch being 0.94).

At Cloudera, we’re committed to ensuring that CDH, our open source distribution of Apache Hadoop and related projects (including HBase), ships with the results of this steady progress. Thus, CDH 4.2 was rebased on 0.94.2, as compared to its predecessor CDH 4.1, which was based on 0.92.1. CDH 4.3 has moved one step further and is rebased on 0.94.6.1.

Cloudera Manager 4.6: Now with Significantly More Free Features

Yesterday we announced the availability of Cloudera Manager 4.6. As part of this release, the Free Edition of Cloudera Manager (now a part of Cloudera Standard) has been enhanced significantly to include many features formerly only available with a subscription license:

With New Product Packaging, Adopting the Platform for Big Data is Even Easier

Today is a big day: Cloudera is not only urging our customers to “Unaccept the Status Quo” (the continued and accelerating spending on data warehousing, expensive data storage, and associated software licenses), but we also announced that Cloudera Search has entered public beta. Now anyone who knows how to do a Google search can query data stored in Cloudera’s Platform for Big Data.

In this post, however, I’d like to explain the new, simpler product naming/packaging structure that will make adopting and deploying Cloudera more straightforward.

Introducing Cloudera Standard

Cloudera Search: The Newest Hadoop Framework for CDH Users and Developers

One of the unexpected pleasures of open source development is the way that technologies adapt and evolve for uses you never originally anticipated.

Seven years ago, Apache Hadoop sprang from a project based on Apache Lucene, aiming to solve a search problem: how to scalably store and index the internet. Today, it’s my pleasure to announce Cloudera Search, which uses Lucene (among other things) to make search solve a Hadoop problem: how to let non-technical users interactively explore and analyze data in Hadoop.

CDH 4.3 is Released!

I’m pleased to announce that CDH 4.3 is released and available for download. This is the third quarterly update to our GA shipping CDH 4 line and the 17th significant release of our 100% open source Apache Hadoop distribution.

CDH 4.3 is primarily focused on maintenance. There are more than 400 bug fixes included in this release across the components of the CDH stack. This represents a great step forward in quality, security, and performance.

Customer Spotlight: King.com’s Climb to the Social Gaming Throne

This week I’d like to highlight King.com, a European social gaming giant that recently claimed the throne for having the most daily active users (more than 66 million). King.com has methodically and successfully expanded its reach beyond mainstream social gaming to dominate the mobile gaming market — it offers a streamlined experience that allows gamers to pick up their gaming session from wherever they left off, in any game and on any device. King.com’s top games include “Candy Crush Saga” and “Bubble Saga”.

And — you guessed it — King.com runs on CDH.

FAQ: Understanding the Parcel Binary Distribution Format

Have you ever wished you could upgrade to the latest CDH minor release with just a few mouse clicks, and even without taking any downtime on your cluster? Well, with Cloudera Manager 4.5 and its new “Parcel” feature, you can!

That release introduced many new features and capabilities related to parcels, and in this FAQ-oriented post, you will learn about most of them.

What are parcels?

Cloudera Development Kit (CDK): Hadoop Application Development Made Easier

Editor’s Note (Dec. 11, 2013): As of Dec. 2013, the Cloudera Development Kit is now known as the Kite SDK. Links below are updated accordingly.

At Cloudera, we have the privilege of helping thousands of developers learn Apache Hadoop, as well as build and deploy systems and applications on top of Hadoop. While we (and many of you) believe that platform is fast becoming a staple system in the data center, we’re also acutely aware of its complexities. In fact, this is the entire motivation behind Cloudera Manager: to make the Hadoop platform easy for operations staff to deploy and manage.

Customer Spotlight: Sneak Peek into Skybox Imaging’s Cloudera-powered Satellite System

This week, the Cloudera Sessions head to Washington, DC, and Columbus, Ohio, where attendees will hear from AOL, Explorys, and Skybox Imaging about the ways Apache Hadoop can be used to optimize digital content, to improve the delivery of healthcare, and to generate high-resolution images of the entire globe that provide value to retailers, farmers, government organizations and more.

I’d like to take this opportunity to shine a spotlight on Skybox Imaging, an innovative company that is putting Hadoop to work to help us see the world more clearly, literally.

How the SAS and Cloudera Platforms Work Together

On Monday April 29, Cloudera announced a strategic alliance with SAS. As the industry leader in business analytics software, SAS brings a formidable toolset to bear on the problem of extracting business value from large volumes of data.

Over the past few months, Cloudera has been hard at work along with the SAS team to integrate a number of SAS products with Apache Hadoop, delivering the ability for our customers to use these tools in their interaction with data on the Cloudera platform. In this post, we will delve into the major mechanisms that are available for connecting SAS to CDH, Cloudera’s 100% open-source distribution including Hadoop.

SAS/ACCESS to Hadoop

Customer Spotlight: Nokia’s Big Data Ecosystem Connects Cloudera, Teradata, Oracle, and Others

As Cloudera’s keeper of customer stories, it’s dawned on me that others might benefit from the information I’ve spent the past year collecting: the many use cases and deployment patterns for Hadoop amongst our customer base.

This week I’d like to highlight Nokia, a global company that we’re all familiar with as a large mobile phone provider, and whose Senior Director of Analytics – Amy O’Connor – will be speaking at tomorrow’s Cloudera Sessions event in Boston.

Cloudera Academic Partnership Program: Creating Hadoop Lovers in Universities Worldwide

Today Cloudera announced a new Cloudera Academic Partnership program, in which participating universities worldwide get access to curriculum, training, certification, and software. 

As noted in the press release, the global demand for people with Apache Hadoop and data science skills is dwarfing all supply. We consider it an important mission to help accredited universities meet that demand, by equipping them with the content and training they need to educate students in the Hadoop arts.

How Persado Supports Persuasion Marketing Technology with Data Analyst Training

This guest post comes from Alex Giamas, Senior Software Engineer on the data warehouse team at Persado, an ultra-hot persuasion marketing technology company with operations in Athens, Greece.

A World-Class EDW Requires a World-Class Hadoop Team

Persado is the global leader in persuasion marketing technology, a new category in digital marketing. Our revolutionary technology maps the genome of marketing language and generates the messages that work best for any customer and any product at any time. To assure the highest quality experience for both our clients and end-users, our engineering team collaborates with Ph.D. statisticians and data analysts to develop new ways to segment audiences, discover content, and deliver the most relevant and effective marketing messages in real time.

It’s Only Rock and Roll

It’s only Rock and Roll, but I like it!
           – Mick Jagger

Copyright is having a tough time in the digital age. New copies of music, movies and software can be created at near zero cost. Some wonder whether it still makes sense to ever charge for content. Over the past century large industries have developed that sell content. These industries resist change. We consumers love our content, but don’t love paying for it. But would all the content we love still exist without payment for copyright?

How-to: Use Vagrant to Set Up a Virtual Hadoop Cluster (For CDH 4)

This guest post comes to us from David Greco, CTO of Eligotech. For a how-to on this subject for CDH 5, see this post.

Vagrant is a very nice tool for programmatically managing many virtual machines (VMs) on a single physical machine. It natively supports VirtualBox and also provides plugins for VMware Fusion and Amazon EC2, supporting the management of VMs in those environments as well.

We Honor the Champions of Big Data!

In the technology business, building a thriving and progressive user ecosystem around a platform is about as Mom-and-apple-pie as you can get. We all intuitively acknowledge that it’s one of the metrics for success.

How-to: Create a CDH Cluster on Amazon EC2 via Cloudera Manager

Editor’s Note (added Feb. 25, 2015): For releases beyond 4.5, Cloudera recommends the use of Cloudera Director for deploying CDH in cloud environments. 

Cloudera Manager includes a new express installation wizard for Amazon Web Services (AWS) EC2. Its goal is to enable Cloudera Manager users to provision CDH clusters and Cloudera Impala (the open source distributed query engine for Apache Hadoop) on EC2 as easily as possible (for testing and development purposes only, not supported for production workloads) - and thus is currently the fastest way to provision a Cloudera Manager-managed cluster in EC2.

How-to: Import a Pre-existing Oozie Workflow into Hue

Hue is an open-source web interface for Apache Hadoop packaged with CDH that focuses on improving the overall experience for the average user. The Apache Oozie application in Hue provides an easy-to-use interface to build workflows and coordinators. Basic management of workflows and coordinators is available through the dashboards with operations such as killing, suspending, or resuming a job.

Prior to Hue 2.2 (included in CDH 4.2), there was no way to manage workflows within Hue that were created outside of Hue. As of Hue 2.2, importing a pre-existing Oozie workflow by its XML definition is now possible.

How to import a workflow

Apache Hadoop Developer Training Helps Query Massive Telecom Data

This guest post is provided by Rohit Menon, Product Support and Development Specialist at Subex.

I am a software developer in Denver and have been working with C#, Java, and Ruby on Rails for the past six years. Writing code is a big part of my life, so I constantly keep an eye out for new advances, developments, and opportunities in the field, particularly those that promise to have a significant impact on software engineering and the industries that rely on it. 

In my current role working on revenue assurance products in the telecom space for Subex, I have regularly heard from customers that their data is growing at tremendous rates and becoming increasingly difficulty to process, often forcing them to portion out data into small, more manageable subsets. The more I heard about this problem, the more I realized that the current approach is not a solution, but an opportunity, since companies could clearly benefit from more affordable and flexible ways to store data. Better query capability on larger data sets at any given time also seemed key to derive the rich, valuable information that helps drive business. Ultimately, I was hoping to find a platform on which my customers could process all their data whenever they needed to. As I delved into this Big Data problem of managing and analyzing at mega-scale, it did not take long before I discovered Apache Hadoop.

Mission: Hands-On Hadoop

Introduction to Apache HBase Snapshots

The current (4.2) release of CDH — Cloudera’s 100% open-source distribution of Apache Hadoop and related projects (including Apache HBase) — introduced a new HBase feature, recently landed in trunk, that allows an admin to take a snapshot of a specified table.

Prior to CDH 4.2, the only way to back-up or clone a table was to use Copy/Export Table, or after disabling the table, copy all the hfiles in HDFS. Copy/Export Table is a set of tools that uses MapReduce to scan and copy the table but with a direct impact on Region Server performance. Disabling the table stops all reads and writes, which will almost always be unacceptable.

How-to: Set Up a Hadoop Cluster with Network Encryption

Hadoop network encryption is a feature introduced in Apache Hadoop 2.0.2-alpha and in CDH4.1.

In this blog post, we’ll first cover Hadoop’s pre-existing security capabilities. Then, we’ll explain why network encryption may be required. We’ll also provide some details on how it has been implemented. At the end of this blog post, you’ll get step-by-step instructions to help you set up a Hadoop cluster with network encryption.

A Bit of History on Hadoop Security

What’s New in Hue 2.2?

This post is about the new release of Hue, an open source web-based interface that makes Apache Hadoop easier to use, that’s included in CDH4.2.

Hue lets you interact with Hadoop services from within your browser without having to go to a command-line interface. It features a file browser for HDFS, an Apache Oozie Application for creating workflows of data processing jobs, a job designer/browser for MapReduce, Apache Hive and Cloudera Impala query editors, a Shell, and a collection of Hadoop APIs.

New Products and Releases: Cloudera Navigator, Cloudera Enterprise BDR, and More

Today is an exciting day for Cloudera customers and users. With an update to our 100% open source platform and a number of new add-on products, every software component we ship is getting either a minor or major update. There’s a lot to cover and this blog post is only a summary. In the coming weeks we’ll do follow-on blog posts that go deeper into each of these releases.

New Products

How-To: Run a MapReduce Job in CDH4 using Advanced Features

In my previous post, you learned how to write a basic MapReduce job and run it on Apache Hadoop. In this post, we’ll delve deeper into MapReduce programming and cover some of the framework’s more advanced features. In particular, we’ll explore:

Ph.D. Interns at Cloudera: Bringing Big Data Back to School

The following is a series of stories from people who in the recent past worked as Engineering Interns at Cloudera. These experiences concretely illustrate how collaboration between commercial companies like Cloudera and academia, such as in the form of these internships, helps promote big data research at universities. (These experiences were previously published in the ACM student journal, XRDS.)

Yanpei Chen (Intern 2011)

Webinar: Introduction to Hadoop Developer Training (Jan. 31)

Are you new to Apache Hadoop and need to start processing data fast and effectively? Have you been playing with CDH and are ready to move on to development supporting a technical or business use case? Are you prepared to unlock the full potential of all your data by building and deploying powerful Hadoop-based applications?

How-to: Deploy a CDH Cluster in Skytap Cloud

You may have seen the recent announcement from Skytap about the availability of pre-configured CDH4 templates in the Skytap Cloud public template library. So for anyone who wants to try out a Cloudera Hadoop cluster—from small to large—it can now be easily accomplished in Skytap Cloud. The how-to below from Skytap’s Matt Sousely explains how.

The goal of this how-to will be to spin up a 10-node Cloudera Hadoop cluster in Skytap Cloud. To begin, let’s talk about the two new Cloudera Hadoop cluster templates. The first is Cloudera CDH4 Hadoop cluster: a 2-node Hadoop cluster template. It includes 2 nodes and a management node/server. The second is the Cloudera CDH4 Hadoop host template. This second template is not intended to run by itself in a configuration—rather, it contains a host VM that is ready to become another Hadoop node in the Cloudera CDH4 Hadoop cluster template-based configuration.

How-to: Do Apache Flume Performance Tuning (Part 1)

The post below was originally published via blogs.apache.org and is republished below for your reading pleasure.

This is Part 1 in a series of articles about tuning the performance of Apache Flume, a distributed, reliable, and available service for efficiently collecting, aggregating, and moving large amounts of event data.

Apache Hadoop in 2013: The State of the Platform

For several good reasons, 2013 is a Happy New Year for Apache Hadoop enthusiasts.

In 2012, we saw continued progress on developing the next generation of the MapReduce processing framework (MRv2), work that will bear fruit this year. HDFS experienced major progress toward becoming a lights-out, fully enterprise-ready distributed filesystem with the addition of high availability features and increased performance. And a hint of the future of the Hadoop platform was provided with the Beta release of Cloudera Impala, a real-time query engine for analytics across HDFS and Apache HBase data.

How Rapleaf Works Smarter with Cloudera

Because raising the visibility of Apache Hadoop use cases is so important, in this post we bring you a re-posted story about how and why Rapleaf, a marketing data company based in San Francisco, uses Cloudera Enterprise (CDH and Cloudera Manager).

Founded in 2006, Rapleaf’s mission is to make it incredibly easy for marketers to access the data they need so they can personalize content for their customers. Rapleaf helps clients “fill in the blanks” about their customers by taking contact lists and, in real time, providing supplemental data points, statistics and aggregate charts and graphs that are guaranteed to have greater than 90% accuracy. Rapleaf is powered by Cloudera.

Business Challenges Before Cloudera

What’s Next for Cloudera Impala?

It’s been an exciting month and a half since the launch of the Cloudera Impala (the new open source distributed query engine for Apache Hadoop) beta, and we thought it’d be a great time to provide an update about what’s next for the project – including our product roadmap, release schedule and open-source plan.

First of all, we’d like to thank you for your enthusiasm and valuable beta feedback. We’re actively listening and have already fixed many of the bugs reported, captured feature requests for the roadmap, and updated the Cloudera Impala FAQ based on user input.

GA Roadmap

How-To: Run a MapReduce Job in CDH4

This is the first post in series that will get you going on how to write, compile, and run a simple MapReduce job on Apache Hadoop. The full code, along with tests, is available at http://github.com/cloudera/mapreduce-tutorial. The program will run on either MR1 or MR2.

We’ll assume that you have a running Hadoop installation, either locally or on a cluster, and your environment is set up correctly so that typing “hadoop” into your command line gives you some notes on usage. Detailed instructions for installing CDH, Cloudera’s open-source, enterprise-ready distro of Hadoop and related projects, are available here: https://ccp.cloudera.com/display/CDH4DOC/CDH4+Installation. We’ll also assume you have Maven installed on your system, as this will make compiling your code easier. Note that Maven is not a strict dependency; we could also compile using Java on the command line or with an IDE like Eclipse.

The Use Case

Secrets of Cloudera Support: The Champagne Strategy

At Cloudera, we put great pride into drinking our own champagne. That pride extends to our support team, in particular.

Cloudera Manager, our end-to-end management platform for CDH (Cloudera’s open-source, enterprise-ready distribution of Apache Hadoop and related projects), has a feature that allows subscription customers to send a snapshot of their cluster to us. When these cluster snapshots come to us from customers, they end up in a CDH cluster at Cloudera where various forms of data processing and aggregation can be performed. 

Introducing Cloudera CDH4 Certification

We are very pleased to introduce new, CDH4.1-aligned versions of the Cloudera Certified Developer for Apache Hadoop and Cloudera Certified Administrator for Apache Hadoop exams.

To celebrate, we’re offering a steep 40% discount on the new exams until the end of the year! Just use the promotion code CDH4 when you register to take the CCD-410 or CCA-410 exam through Pearson VUE before Dec. 31, 2012.

New: Cloudera Manager Free Edition Demo VM

With the availability of this new demo VM containing Cloudera Manager Free Edition and CDH4.1.2 on CentOS 6.2, getting quick hands-on experience with a freeze-dried single-node Apache Hadoop cluster is just a few minutes away after the download process. 

This new addition to our growing Demo VM menagerie is available, as usual, in VMware, VirtualBox, and KVM flavors. A 64-bit host OS is required.

Meet the Engineer-Turned-Product Manager: Eva Andreasson

Eva

In this installment of “Meet the Engineer”, meet Eva Andreasson (@EvaAndreasson), a former Java programmer currently working with Cloudera engineers as the product manager for CDH.

Top Five Nominees for the 2012 Government Big Data Solutions Award

The following is a re-post from Bob Gourley of CTOVision.com.

The amount of data being created in governments is growing faster than humans can analyze. But analysis can solve tough challenges. Those two facts are driving the continual pursuit of new Big Data solutions. Big Data solutions are of particular importance in government. The government has special abilities to focus research in areas like Health Sciences, Economics, Law Enforcement, Defense, Geographic Studies, Environmental Studies, Bioinformatics, and Computer Security. Each of those area can be well served by Big Data approaches, and each has exemplars of solutions worthy of highlighting to the community.

Analyzing Twitter Data with Apache Hadoop, Part 3: Querying Semi-structured Data with Apache Hive

This is the third article in a series about analyzing Twitter data using some of the components of the Apache Hadoop ecosystem that are available in CDH (Cloudera’s open-source distribution of Apache Hadoop and related projects). If you’re looking for an introduction to the application and a high-level view, check out the first article in the series.

In the previous article in this series, we saw how Flume can be utilized to ingest data into Hadoop. However, that data is useless without some way to analyze the data. Personally, I come from the relational world, and SQL is a language that I speak fluently. Apache Hive provides an interface that allows users to easily access data in Hadoop via SQL. Hive compiles SQL statements into MapReduce jobs, and then executes them across a Hadoop cluster.

What’s New in CDH4.1 Mahout

Cloudera recently announced the general availability of CDH4.1, an update to our open-source, enterprise-ready distribution of Apache Hadoop and related projects. Among various components, Apache Mahout is a relatively recent addition to CDH (first added to CDH3u2 in 2011), but is already attracting increasing interest out in the field. 

Mahout started as a sub-project of Apache Lucene to provide machine-learning libraries in the area of clustering and classification. It later evolved into a top-level Apache project with much broader coverage of machine-learning techniques (clustering, classification, recommendation, frequent itemset mining etc.). 

Quorum-based Journaling in CDH4.1

A few weeks back, Cloudera announced CDH 4.1, the latest update release to Cloudera’s Distribution including Apache Hadoop. This is the first release to introduce truly standalone High Availability for the HDFS NameNode, with no dependence on special hardware or external software. This post explains the inner workings of this new feature from a developer’s standpoint. If, instead, you are seeking information on configuring and operating this feature, please refer to the CDH4 High Availability Guide.

Background

Since the beginning of the project, HDFS has been designed around a very simple architecture: a master daemon, called the NameNode, stores filesystem metadata, while slave daemons, called DataNodes, store the filesystem data. The NameNode is highly reliable and efficient, and the simple architecture is what has allowed HDFS to reliably store petabytes of production-critical data in thousands of clusters for many years; however, for quite some time, the NameNode was also a single point of failure (SPOF) for an HDFS cluster. Since the first beta release of CDH4 in February, this issue has been addressed by the introduction of a Standby NameNode, which provides automatic hot failover capability to a backup. For a detailed discussion of the design of the HA NameNode, please refer to the earlier post by my colleague Aaron Myers.

Limitations of NameNode HA in Previous Versions

Cloudera Manager 4.1 Now Available; Supports Impala Beta Release

I am very pleased to announce the availability of Cloudera Manager 4.1. This release adds support for the Cloudera Impala beta release, and management and monitoring of key CDH features.

Here are the highlights of Cloudera Manager 4.1:

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