Understanding disk inodes

You try creating a file on a server and see this error message: No space left on device ...but you've got plenty of space: df Filesystem 1K-blocks Used Available Use% Mounted on /dev/xvda1 10321208 3159012 6637908 33% / Who is the invisible monster chewing up all of your space? Why, ... Read more

From Ruby to Go: a rewrite for the future

During a team camp among the lofty peaks of Breckenridge, Colorado, we talked a lot about the future of Scout and monitoring in general. Big mountains and nature have a way of doing that. One thing that was getting our nerd juices flowing: Go . At Monitorima in May, it ... Read more

From MySQL+MMM to MariaDB+Galera Cluster: A High Availability Makeover

Kevin Lawver , President @ Rails Machine , is our guest author for this post. Few things feel worst than rolling out a High Availability (HA) system, then regularly seeing that system collapse. For our team at Rails Machine, that failing HA system was MySQL Multi-Master Replication Manager (MMM) . ... Read more

Docker: Git for deployment

I've been hearing how Docker is the new awesome, but it didn't click for me until I dug in with a practical question: if we deployed Scout via Docker, would deployment be a more pleasurable experience? My three takeaways are below. Finally, an efficient way to simulate our production environment ... Read more

Understanding CPU Steal Time - when should you be worried?

A big thanks to Eric Lindvall of Papertrail for adding steal time to Scout's CPU Usage Plugin and helping out on this blog post! Netflix tracks CPU Steal Time closely. In fact, if steal time exceeds their chosen threshold, they shut down the virtual machine and restart on a different ... Read more

The Short and Sweet SSL How-to

Got a site you need to serve up via SSL ? Here are your Cliffs notes. This assumes 1) your site already runs without SSL ; 2) you’re using Apache and Ubuntu; 3) you don’t want any browser warnings, so no self-signed certificates. 1. Generate a Private Key $ openssl ... Read more

Detect and Fix HAProxy+Apache+Passenger Queue Backlogs

To inspire hard work, some young men hang a poster on their wall that includes: (1) an exotic sports car (2) a scantly clad lady and (3) a beach house. My inspirational poster would be much less attractive: a friendly butler who offers time-honored wisdom (with an accent because people ... Read more

Determining free memory on Linux

When checking the amount of free memory on a Linux server, it’s easy to think you’re running out of memory when you’re not. For example, here’s the output of free -m on a server with 4GB of RAM : With a quick glance, you might start sweating. Only 39 MB ... Read more

Embedded Customer Support With Rapportive

A big part of providing good support is making it painless. At Scout , Andre and I handle all of the support requests. Once we’ve gathered the account information, it usually doesn’t take much time to help. The problem is quickly putting the account information together. We don’t want to ... Read more

RVM and cron in production

UPDATED 6/7/2013 – We no longer recommend using bash -l -c to run Cron jobs with RVM . See our updated approach . This info is for Scout users, but it’s also applicable to anyone who’s wondered how to use cron together with RVM . This assumes 1) you are ... Read more

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