Tag: SysAdmin

While working on a few tasks in the past few weeks, I faced a problem that involved setting a “filter” for an application that was exposed to the internet. The application receives requests with some data, processes it and then…

Cron is not standard! Most distributions treat cron as if it were a standard, but almost no two distributions actually use the same cron daemon. Debian uses Dillon’s Cron which places an emphasis on being lightweight. CentOS uses Vixie Cron…

After looking at how virtual CPUs are handled in Amazon Web Services and Microsoft Azure, we explore CPU definitions and CPU performance under the Google Compute Engine platform.

Creating a Consul Client Docker Image In my previous post, I demonstrated how to create a cluster of Consul servers using a pre-built Docker image. I was able to do this because our use case was simple: run Consul. In…

Today I would like to demonstrate the use of Consul to help achieve loose coupling and discovery of services, two important principles of service-oriented architecture (SOA) present in modern, elastic infrastructures. If you have ever designed an architecture to be…

After observing CPU core sharing with Amazon Web Services EC2, I thought it would be interesting to see if Microsoft Azure platform exhibits the same behavior. Signing up for Azure’s 30-day trial gives $200 in credit to use over the…

There are many scenarios when a SysAdmin has to do a “box walk” of the entire infrastructure to execute a command across many servers. This is universally accepted as one of the less glamorous parts of our job. The larger…

I’ve been doing some testing to clarify what a vCPU in Amazon Web Services actually is. Over the course of the testing, I experienced inconsistent results on a 2-thread test on a 4-vCPU m3.xlarge system, due to the mislabeling of…

The definition of a vCPU in Amazon Web Services is a bit unclear. We run some tests to see how much CPU performance we actually get, and discover some unexpected side effects from AWS’s implementation.

I was contacted by a colleague about a problem he was having. “I’m trying to set up something simple which I’ve done millions of times, but it’s not working. I might be missing something obvious.” The issue was that the…