On Linux qemu-nbd can be used to access disk images in different formats as if they were block devices. For example, to mount a VHD file run To unmount and disconnect the nbd device run
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.
Thankfully the Fedora Project provides cloud images that can be directly used or easily modified to run on almost any cloud environment. Though sometimes, it can be handy to build your own image.
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 »
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 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 »
To temporarily change a console’s keyboard mapping there’s loadkeys, a little user space program that allows you to alter the kernel’s keyboard mapping. Loading the very handy US International keyboard layout, use To list the currently used keyboard layout or all available keyboard layouts, localectl can be used If localectl is not available, keyboard mapping files are usually found at… Read more »
If you try to start a graphical application on a minimal Fedora or CentOS setup, e.g. via ssh -X, you might face the situation that the program actually starts up, but no font appears (or a weird one, or only squares where the letters are supposed to be). If you start a program that uses Pango, like firefox, you get… Read more »
Running PulseAudio in system mode is usually a bad idea. There are use cases however, where PulseAudio’s system mode is a great tool, e.g. for building a PulseAudio streaming target to stream audio from multiple clients to speakers. First, install PulseAudio, avahi (a free implementation of zeroconf) to publish the service throughout the network and the corresponding PulseAudio module: Since… Read more »
There’s a bug in Fedora 20 and RHEL 7, where the legacy network service does not set the default route properly. This is due to the fact, that the network service does not evaluate the GATEWAY0 directive in /etc/sysconfig/network-scripts/ifcfg-ethX that is used by NetworkManager. To set the default route with the legacy network service, simply change GATEWAY0 to GATEWAY: Of… Read more »