July 15, 2013

Fedora 18: Noticing Clock Skew?

Recently I noticed that my clock was beginning to skew, and NTP wasn’t able to keep up with it.  This is due to having a “system clock” and a “hardware clock” the system clock is the one that the OS controls, while the hardware clock is controlled by the BIOS and runs on the hardware.  So all I did to resolve it was sync up […]
June 17, 2013

Media Management: Rename JPG Images Based on Metadata

I have been doing a bit of cleanup around my home file server, and have noticed that while I have a really beautiful collections of family photographs there is no logical organization around these photos.  I have many duplicates names, which would collide in the event of trying to merge multiple directories, and even worse I have many duplicate copies of pictures from various uploads […]
March 4, 2013

Oracle Linux 6: Create an OCFS2 Cluster and Filesystem

Today we are going to go through the process of creating a clustered file system on a pair of Oracle Linux 6.3 nodes.  This exercise is not very resource intensive.  I am using two VMs each with 1GB of RAM a single CPU and a shared virtual disk file in addition to the OS drivers. The Basic Concepts Now why is a clustered file system […]
January 31, 2013

Sudo: Setting Up Intelligent Security Policies Part Two

In Part One we went over the basics of sudo, what it is, why we use it, and how it is used properly.  In this article we are going to take it a step further and look at specific use cases for sudo.  The key thing to remember though, is that you have two ways you can use sudo, 1) to allow for program execution […]
January 30, 2013

Sudo: Setting Up Intelligent Security Policies Part One

What is Sudo? Prior to sudo whenever you wanted to run a command as a specific user then you would su (switch user) to gain access to a shell for that user.  This of course required that you knew the password for that user, and it would spawn a new shell after successful authentication.  The major drawback to this was that in order to allow […]
October 24, 2012

Linux KVM: Ubuntu 12.10 with Openvswitch

Today I am revisiting my previous post on Openvswitch on Ubuntu 12.04.  Things have changed since then.  Previously Openvswitch was relatively new and as such the userland tools (with libvirt being the one I use) didn’t support it yet, so while you could have used Openvswitch by executing the kvm processes for each VM manually.  Since this was a predictable problem the Openvswitch guys created […]
August 20, 2012

Linux-LVM: Resize Partition to Grow LVM Volume Group

Logical Volume Manager makes the dynamic expansion of file systems dead stupid simple.  However there is a weakness, if you are using a partitioned file system as your Physical Volume (PV) then you will end up needing to expand the file system if you ever need to grow the actual storage.  This can be avoided by using the actual physical device /dev/sda as the PV, […]
August 2, 2012

Bash: Automatically Mount File Systems on Volume Group if Present

Update 09/16/2015 – I have published an updated article for this here: http://blog.allanglesit.com/2012/08/bash-automatically-mount-file-systems-on-volume-group-if-present/ In my laptop I have a solid state disk, and frankly I am way past addicted to solid state disks, but what you get in performance you lose in capacity.  As such I have had to be creative with how I can have the capacity and the performance that I need.  Lately the […]
June 11, 2012

Linux-KVM: Using KVM on Oracle Linux 6

In my new role I am using Oracle Linux more and more, so as an exercise I have been replicating my builds on Oracle Linux.  Here we are going to use Oracle Linux 6.2 x86_64 as a KVM hypervisor.  Keep in mind that KVM is not Oracle’s preferred hypervisor, however it is supported, but if you plan on taking advantage of the reduced software licensing […]
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