Author Archives: admin

Converting a disk image to VHD for Azure

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Currently the Fedora projects provides cloud images as qcow2 and raw disk files. Microsoft’s Azure however only supports VHD files. Fortunately qemu-img can convert between those formats: Note that the subformat options fixed and force_size are required for Azure to be able to use the disk image since Azure only supports fixed sized disks.

Running Fedora 27 on Google Compute Engine

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Usually Linux distributions with a long life cycle like RHEL (or its free derivative CentOS), Debian or SLES are the way to go for virtual machines in a cloud environment. But sometimes you need to be a little bit closer to upstream. Maybe because your applications relies on newer version of some packages that are not (easily) available on distributions… Read more »

Allow blacklisted VMWare Workstation Player graphics driver

For some reason, VMWare decided to blacklist some graphics drivers for their VMware Workstation Player. That includes the Mesa DRI drivers for most Intel IGPs, which results in unbearably slow graphic performance and potentially error messages such as “Hardware graphics acceleration is not available” or “No 3D support is available from the host” when starting a virtual machine To enable… Read more »

Arduino development with Eclipse

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The Arduino IDE is great for beginners: It makes it really easy to write simple programs without having to care about compiler options, include paths, language standards or how to actually flash firmware onto the microcontroller. It even comes with a built-in serial monitor which can be a great tool for debugging. Inevitably, as people dive deeper into the world… Read more »

Updating BIOS firmware via iPXE

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These days mainboards usually come with some sort of wizbang tool that allow the user to update the BIOS from a USB drive or straight via network. Except, of course, that one single mainboard that absolutely needs a new BIOS version on a late Friday afternoon. And obviously the manufacturer only provides a flash tool for DOS and the mainboard… Read more »

Migrating a virtual machine from KVM to ESXi

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Migrating a virtual machine from one host to another is usually no big deal if both hosts run the same VMM. But what if one wants to move a VM from a host running a different hypervisor than the target host? In the case of moving a VM from KVM to ESXi that’s just not (easily) possible. However, one can… Read more »

OpenSSH cipher performance

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The achievable speed of copying a file with OpenSSH (e.g. with scp) will depend on quite a few different factors such as CPU speed, CPU architecture, Network throughput, OpenSSH implementation, OS, hard drive speed, etc. But how much of a difference does choosing a different cipher algorithm make? And what’s the fastest OpenSSH cipher algorithm? Turns out, there’s no simple… Read more »

Netbeans’ tomcat log file path

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Spawning a tomcat server instance from within Netbeans is really handy for rapid Java Servlet or JavaServer Pages application development. Since log levels are usually quite verbose during development, logs tend to pile up. So you might want to clean out the log directory from time to time. Or maybe you just want to go through one of those logs… Read more »

Creating a zfs pool on RAM backed block devices

Especially for performance benchmarks it can be quite handy to have a zfs pool that’s not limited by the speed of the underlying hard drives or other block devices (like iSCSI or fibre channel). The Linux kernel has a nice block device driver that let’s you create virtual block devices that are RAM backed. To list the available options, use… Read more »