Fixing “unable to find partition containing kernel” on XenServer with Ubuntu VM

Sometimes an Ubuntu VM doesn’t start up anymore on XenServer. The following error is shown in XenCenter: Error: Starting VM ‘My VM’ – Using <class ‘grub.GrubConf.Grub2ConfigFile’> to parse /grub/grub.cfg – WARNING:root:Unknown directive load_video – WARNING:root:Unknown directive terminal_output – WARNING:root:Unknown directive else – WARNING:root:Unknown directive elif – WARNING:root:Unknown directive else – WARNING:root:Unknown directive else – WARNING:root:Unknown […]

Storm in pictures

We’ve been using Storm for some time now. It is quite easy to start using it in a local environment (e.g. your IDE), but it can be a bit daunting to install a cluster and then really understand what Storm is actually doing to execute your topology. The documentation has improved over time, and some […]

Installing OpenStack with DevStack

OpenStack is open source software for building private and public clouds. There are several ways to install OpenStack. This guide will walk you through the installation of DevStack, which is a documented shell script to build complete OpenStack development environments. We will start with the installation of Ubuntu 12.04 (LTS). Make sure that you create […]

Restoring backup of VM in XenServer

In a previous article we looked at backing up running VMs in XenServer. In this article, we will see how a backed up VM can be restored. Login to the console of the host machine you want the restored VM to be placed on, and issue the following command: xe vm-import filename=”/path/to/backed-up-vm.xva” preserve=true The path […]

Deployment Strategies for Distributed Applications on Cloud Computing Infrastructures

I presented a paper called Deployment Strategies for Distributed Applications on Cloud Computing Infrastructures at the 5th International Conference on Cloud Computing Technology and Science (IEEE CloudCom 2013). Cloud computing enables on-demand access to a shared pool of IT resources. In the case of Infrastructure as a Service (IaaS), the cloud user typically acquires Virtual […]

WebSocket tutorial with Java server (Jetty) and JavaScript client

WebSocket is a web technology providing full-duplex communications channels over a single TCP connection. WebSocket is designed to be implemented in web browsers and web servers, but it can be used by any client or server application. In this tutorial we will use a Java server and a JavaScript client. We start with the Java […]