Managing Computers with Automation
Using virtualization to provide "HA at wholesale"
Traditionally, the way people have implemented high availability is by using a high-availability management package like Linux-HA, then configure it in detail for each application, file system mount, IP address and so on. This traditional m
Posted: Oct. 23, 2008 05:18 PM
Watch that basket!
The computing industry has lots of trends, numerous buzzwords, and a number of hot topics. Sometimes these are in conflict with each other, or at least start out that way... But, in the end, there are often good ways to...
Posted: Jun. 10, 2008 11:10 AM
Virtual machine snapshots considered (nearly) worthless...
With apologies to Edgar Dijkstra... Usually when people talk about virtual machine snapshotting, they include with it snapshotting both the server and any filesystems its directly connected to. Although this is more complex than just snapshotting the
Posted: Mar. 12, 2008 04:21 PM
A Complete Cluster Stack for Linux
Recently, I've had some folks ask me offline what exactly would a “complete” Linux cluster stack look like. That's a good question, and this posting is intended to address that question. So let's start with – what kind of cluster?...
Posted: Jan. 8, 2008 12:21 AM
How Managed Virtualization (including HA) conflicts with System Management
Managed Virtualization Versus System Management In an earlier post, I talked about a couple of kinds of virtualization, comparing two of them and highlighting their strengths. This posting discusses how virtualization can confuse and confound conv
Posted: Dec. 13, 2007 11:54 PM
A brief overview of load balancing techniques
Something that people commonly do which involves a form of automation is load balancing. Load balancing is the idea that incoming network requests are distributed across a set of servers which then each provide the same service. If you spread...
Posted: Dec. 4, 2007 10:59 PM
Quorum Server Illustrated - updated
In two earlier posts  , I gave brief descriptions of the quorum server which seem to have left as much confusion as they provided clarity. This post is only about the Linux-HA quorum server, and includes illustrations for clarity....
Posted: Nov. 27, 2007 03:49 PM
Alan eats his own cl_respawn dog food. Yum!!
In this posting, I show how to use cl_respawn to monitor my system logging and help keep it running, and along the way, I improved cl_respawn a little as well. In addition, I explain why I couldn't just use the...
Posted: Nov. 12, 2007 02:01 AM
Availability, MTBF, MTTR and other bedtime tales
If we let A represent availability, then the simplest formula for availability is: A = Uptime/(Uptime + Downtime) Of course, it's more interesting when you start looking at the things that influence uptime and downtime. The most common measures that.
Posted: Nov. 4, 2007 06:07 PM
More about quorum - updated
In a previous article, I talked about quorum, and alluded to some more details about quorum which I'll discuss here in a little more detail. Let's examine a couple of common quorum tie-breaker methods, and see what's useful, and what's...
Posted: Oct. 31, 2007 07:41 AM
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