My name is Philipp C. Heckel and I write about nerdy things.
For my job, I work with file systems and image files a lot: Every day, we mess with Grub, the partition tables (MBR/GPT), EFI and BIOS systems, etc. So pretty much every day, I need to boot some image file or investigate why some image didn’t boot.
This (super duper) short post shows how to boot image files using straight kvm commands.
Have you ever rebooted your computer only to see a black screen with a blinking cursor? If you have a USB drive attached, chances are the blinking cursor is caused by invalid bootstrap code in the Master Boot Record (MBR) on that drive which has caused the normal boot execution to stop without returning control to the BIOS. If you have physical access to the machine, simply remove the USB drive and/or change the boot order to pick the OS disk first.
If you have no physical access, things are a bit more tricky: This exact thing happened to me at work the other day. Unfortunately, it didn’t happen to my computer, but to a few dozen of our customer backup appliances during their scheduled upgrade/reboot. Now, while dozens out of over 60k isn’t that much, our customers rely on these devices, so it’s not acceptable to have them not boot properly.
In this short post, I’ll demonstrate how to reproduce the blinking cursor problem, and how to “fix” the MBR to ensure the computer still boots, regardless of the boot order.
In the last few years, the importance of the Internet has risen constantly and made it indispensable for businesses and most individuals to be on-line around the clock. One of the greatest drivers of this development was and still is the shift of the traditional one-to-many Web to an advanced, participatory version of the Word Wide Web. Rather than only making editorial information accessible to many users, the Web 2.0 encourages participation and enables user generated contributions. Leveraging this new paradigm, services like Flickr, Facebook, or Twitter have become very prominent examples for this development.
An essential part of this evolution, but mostly hidden to the end-consumer, is the set of tools that enable these large scale applications. Cloud computing is a relatively new technology that serves as underlying architecture for most of these platforms. By providing virtualized computing resources as a service in a pay-as-you-go manner, cloud computing enables new business models and cost effective resource usage. Instead of having to maintain their own data center, companies can concentrate on their core business and purchase resources when needed. Especially when combining a privately maintained virtual infrastructure with publicly accessible clouds in a hybrid cloud, the technology can open up new opportunities for businesses and help consolidating resources.
However, since cloud computing is a very new term, there are as many definitions of its components as there are opinions about its usefulness. Most of the corresponding technologies are only a few years old and the toolkits lack of maturity and interoperability.
This article introduces the basic concepts of cloud computing and discusses the technical requirements for setting up a hybrid cloud. It briefly looks into security concerns and outlines the status quo of current cloud technologies. In particular, it evaluates several existing cloud toolkits regarding its requirements, occurring problems and interoperability.
In the last few years, the Internet has become increasingly important in various fields of our lives. Not only personal households have discovered the nearly endless possibilities of the Web, but also companies found many different ways of gaining revenue through the online world. Most of the global players and many medium-sized IT companies have realized what opportunities the Web and its technologies provide and used them to build up new services for consumers and businesses. In order to compete with the evolving market, companies of traditional business areas such as newspapers or TV broadcasting companies had to diversify their product lines and are forced to react in a fast, flexible and cost efficient way on every day’s changes of demands and technologies. In fact, every company has to adapt these technologies efficiently to have a chance in the growing market.
As it brings its benefits, cost savings and new customers, every new technology also comes with the more or less known downsides. Even if IT managers are qualified to consider most of the details in how to use and implement them, new software, hardware or resources will – no matter what – always cause unpredicted problems. Due to the IT dependence of today’s companies, every downtime, bug or system overload of a production system directly results in declining profits and higher costs. Especially for service providers, every downtime is business critical to many dependent companies and has to be prevented.
Therefore, companies spend a considerably high amount of money and time to create a stable, flexible and extensible IT environment that supports their business by minimizing risks, increasing availability and allowing to provide better service levels to customers.
Virtualization is a key technology that addresses to achieve these goals. It allows to run multiple virtual computers on the same physical system. By creating an abstraction of the underlying hardware, it allows to execute a variety of virtual machines (VMs) on top of a virtualized hardware.
This article will discuss how the technology of virtualization works, what advantages it offers and why it is an essential part of today’s data centers. The focus will be the server virtualization solution VMware Infrastructure, the flagship product suite of VMware Inc.
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