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
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.
I did not intent to do much editorializing on this site but after a rather frustrating week I thought that perhaps this might provide some stress relief.
This past week I have been working in the lab on standing up a Microsoft Office Sharepoint CMS for the purpose of testing. This CMS consisted of two separate servers runing Microsoft Windows Server 2008, Microsoft SQL Server 2008, and Microsoft Office SharePoint Server 2010. Up until this point my customers really haven’t been using Server ’08 so I looked forward to getting a bit of hands-on time with the O/S. The experience was not pleasant. Read more
Working on both Windows and Linux systems its easy to see the strengths of each platform. One thing that I really like about Windows environment is the existence of small portable applications. These are usually a simple executable which require no installation and few if any dependencies.
While I would take the power of Linux any day over Windows sometimes I wish I had some more small and portable tools. This is where HTTPi comes in. HTTPi is a small portable web (http) server written in Perl. Since Perl is part of the Linux Standard Base you know it will run without needing any dependencies. Read more
The Internet is a scary place and that isn’t going to change anytime soon. As history has shown us time and time again, the “Black-Hats” always manage to stay a step or two ahead of the rest of us. Even the largest companies on the Internet are constantly fighting a battle for the security of their data. The question is, how do regular folks take advantage of the power of the Internet without putting all their data at risk? Read more