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This article is Part 1 in series that will take a closer look at the architecture and methods of a Hadoop cluster, and how it relates to the network and server infrastructure. The content presented here is largely based on academic work and conversations I’ve had with customers running real production clusters. If you run production Hadoop clusters in your data center, I’m hoping you’ll provide your valuable insight in the comments below. Subsequent articles to this will cover the server and network architecture options in closer detail. Before we do that though, lets start by learning some of the basics about how a Hadoop cluster works. OK, let’s get started!

I was cleaning out a stack of old papers and ran across a copy of “The Eight Fallacies of Distributed Computing” that I’d made back in 2004. As Wikipedia puts it, a guy by the name of Peter Deutsch “asserted that programmers new to distributed applications invariably make a set of assumptions… and these assumptions […]

IEEE 802.1AB LLDP specification will enable LAN devices to inform each other about their configurations, thus eliminating misconfiguration problems in networking designs.

I read two great blog posts on Sunday: evergreen Fallacies of Distributed Computing from Bob Plankers and forward-looking Understanding Hadoop Clusters and the Network from Brad Hedlund. Read them both before continuing (they are both great reads) and try to figure out why I’m mentioning them in the same sentence (no, it’s not the fact that Hadoop uses distributed computing).

Every Data Center fabric technology has to integrate seamlessly with legacy equipment running the venerable Spanning Tree Protocol (STP) or one of its facelifted incarnations (for example, RSTP or MST). The alternative, called rip-and-replace when talking about other vendors’ boxes or synchronized upgrade when promoting your wares (no, I haven’t heard it yet, but I’m sure it’s coming), is simply indigestible to most data center architects. TRILL and Cisco’s proprietary Fabric Path take a very definitive stance: the new fabric is the backbone of the network routing TRILL-encapsulated layer-2 frames across bridged segments (TRILL) or contiguous backbone (Fabric Path). Both architectures segment the original STP domain into small chunks at the edges of the network as shown in the following figure:

Every time I mention that Cisco IOS had Local Area Mobility (LAM) (the feature that would come quite handy in today’s virtualized data centers) more than a decade ago, someone inevitably asks “why don’t we use it?” LAM looks like a forgotten step-child, abandoned almost as soon as it was created (supposedly it never got VRF support). The reason is simple (and has nothing to do with the size of L3 forwarding tables): LAM was always meant to be a short-term kludge and L3 gurus never appreciated its potentials.

Is the VXLAN standard just another way to rid the virtual environment of pesky network engineers? Is the VXLAN standard actually better than VLANs? Fast Packet blogger Ivan Pepelnjak explains.

Thirty years ago, Linus Torvalds was a 21 year old student at the University of Helsinki when he first released the Linux Kernel. His announcement started, “I’m doing a (free) operating system (just a hobby, won't be big and professional…)”. Three decades later, the top 500 supercomputers are all running Linux, as are over 70% of all smartphones. Linux is clearly both big and professional.

Linux and flexibility go hand in hand, and the options for virtualization are no different. But recently, a change in the Linux virtualization landscape has appeared with the introduction of the Kernel virtual Machine, or KVM. KVM is the first virtualization solution to be part of the mainline Linux kernel (V2.6.20). KVM supports the virtualization of Linux guest operating systems -- even Windows with hardware that is virtualization-aware. Learn about the architecture of the Linux KVM as well as why its tight integration with the kernel may change the way you use Linux.

Embracing HTTP error code 410 means embracing the impermanence of all things.

No matter how carefully you design and structure your site, visitors will sometimes request missing, moved, or non-existent pages. A well tempered 404 error page will plunge these visitors back int…

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Peer-to-Peer Communication Across Network Address Translators

I swapped my MacBook for an iPad+Linode On September 19th, I said goodbye to my trusty MacBook Pro and started developing exclusively on an iPad + Linode 512. This is the surprising story of a month...

Writings, screencasts, and talks by Zach Holman. Zach works at GitHub and enjoys consuming cherry pies.