I hear a lot of people talking about cloud native applications these days. This includes technologists and business managers. I have found that there really is a spectrum of meaning for the term cloud native and that two people rarely mean the same thing when they say cloud native. At one end of the spectrum would be running a traditional workload on a virtual machine. In this scenario the virtual host may have been manually provisioned, manually configured, manually deployed, etc. It’s cloudiness comes from the fact that it’s a virtual machine running......
Continue Reading
I previously explained how to get one-minute resolution in Munin. The process to get sub-minute resolution in Munin is more tricky. The main reason it’s more tricky is that cron only runs once per minute, which means data must be generated and cached in between cron runs for collection when cron runs. In the case where a single datapoint is collected each time cron runs, the time at which cron runs is sufficient to store the data in rrd. With multiple datapoints being collected on a single cron run, it’s necessary to embed......
Continue Reading
I’ve recently been conducting some performance testing of a PaaS solution. In an effot to capture specific details resulting from these performance tests and how the test systems hold up under load, I looked into a few monitoring tools. Munin caught my eye as being easy to setup and having a large set of data available out of the box. The plugin architecture also made it attractive. One major drawback to Munin was the five minute resolution. During performance tests, it’s necessary to capture data much more frequently. With the latest Munin, it’s......
Continue Reading
Munin is a monitoring tool which captures and graphs system data, such as CPU utilization, load and I/O. Munin is designed so that all data is collected by plugins. This means that every built in graph is a plugin that was included with the Munin distribution. Each plugin adheres to the interface (not a literal OO inteface), as shown below. Munin uses Round Robin Database files (.rrd) to store captured data. The default time configuration in Munin collects data in five minute increments. Some important details: Plugins can be written in any language,......
Continue Reading
In the process of tuning the performance of a MongoDB replica set, it’s useful to be able to observe mongod directly, as opposed to inferring what it’s doing by watching the output of top, for example. For that reason MongoDB comes with a utility, mongotop. The output of mongotop indicates the amount of time the mongod process spend reading and writing to a specific collection during the update interval. I used the following command to run mongotop on an authentication enabled replica set with a two second interval. [watrous@d1t0156g ~]# mongotop -p -u......
Continue Reading
One of my applications runs on a large assortment of hosts split between various data centers. Some of these are redundant pairs and others are in load balanced clusters. They all require a set of identical files which represent static content and other data. rsync was chosen to facilitate replication of data from a source to many targets. What rsync lacked out of the box was a reporting mechanism to verify that the collection of files across target systems was consistent with the source. Existing solutions Before designing my solution, I searched for......
Continue Reading