Most modern filesystems allow you to create virtual disk files without pre-allocating disk space. These virtual disks grow in size as the space is needed. The default virtual disk image type in KVM/QEMU is a sparse “raw” disk image which consumes real disk space as files are added. Interestingly, when files are deleted the virtual disk does not shrink. This makes sense as deleting files from a filesystem doesn’t typically erase the data but only the reference to where the data is stored on the disk. What follows is a recipe to reclaim this disk space. Read more
Not too long ago VMware has a product called “VMware Server” which originally came with a dedicated management application. Later VMware threw out the console and created a web interface for VMware Server. Not long after that they completely threw VMware Server away in favor of their new enterprise software solution(s) ESX/ESXi/vCenter/vSphere/etc. For the new(ish) VMware Workstation 8 one of the most notable features is the “Shared VMs” which is more or less a reawakening of their original VMware Server application functionality. With this feature you can once again set VMs to run in the background, autostart, and access via network. However a problem arises with the installation on systems which use insserv. Read on and I’ll explain the problem and show you how to fix it. Read more
I happen to use quit a diversity of VMware products both for personal use and work. On my work laptop I have been using VMware Workstation now for a few years. When working with ESX(i) or VMware virtualization technologies in general I used to love some of the great lesser documented utilities which comes with Workstation. Two utilities that I have used rather extensively were vmware-mount and vmware-vdiskmanager. After upgrading to the latest VMware Worstation v8 I was super impressed with some of the great new features. However, when trying to convert a virtual disk (vmdk) using vmware-vdiskmanager I was awfully disappointed to see some functionality left out on this version. Read more
Anyone trying to take the deep dive into Linux High Availability (HA) Clustering Technologies might find themselves quickly confused. There seems to be several different software pieces to the Linux clustering scene such as Heartbeat, Pacemaker, Corosync, OpenAIS, cman, rgmanager, and more. Furthermore, choosing which software to use and how to configure it often presumes that the cluster designer/administrator already knows what they need and what they don’t. What is needed for most people is both an overview of clustering technologies and perhaps a slight history lesson in how Linux HA Clustering Technologies have evolved.