Playing around with benchmarks

So I just rebuilt my little home server RAID from LVM+Ext4 to ZFS, changing the layout from RAID5 to RAID1+0, consisting of a pool of two mirrored disk sets.

Since I’m a cheap bugger frugal, I still run a small HP MicroServer Gen7 (N54L) with only 2 GB of RAM, which I’ve filled up with 4 x 3 TB WD RED drives for storage, and a 60 GB SSD for the system.

As everybody knows, the only difference between screwing around and science is writing it down. I was slightly too eager to get started to remember to benchmark my old file system, so I guess any future changes will have to be compared to the current set-up. Continue reading “Playing around with benchmarks”

Monitoring Keepalived with SNMP on Ubuntu 14.04

Introduction

Using keepalived in combination with a couple of HAProxy instances is a convenient yet powerful way of ensuring high availability of services.

Network map, Normal
Load balancer pair in normal state

Up until now, I’ve considered it enough to monitor the VMs where the services run, and the general availability of a HAProxy listener on the common address. The drawback is that it’s hard to see if the site is served by the intended master or the backup load balancer at a glance. The image to the right shows the intended – and at the end of this article achieved – result, with the color of the lines between nodes giving contextual information about the state of the running services.

Monitoring state changes could naïvely be achieved by continuously tailing the syslog and searching for “entered the MASTER state”. This would be a pretty resource-intensive way of solving the issue, though. A less amateurish way to go about it would to use keepalived’s built-in capability of running scripts on state changes, but there are a number of situations in which you can’t be sure that the scripts are able to run, so that’s not really what we want to do either.

Fortunately, keepalived supports SNMP, courtesy of the original author of the SNMP patch for keepalived, Vincent Bernat. In addition to tracking state changes, it potentially allows us to pull out all kinds of interesting statistics from keepalived, as long as we have a third machine from which to monitor things. Let’s set it up. Continue reading “Monitoring Keepalived with SNMP on Ubuntu 14.04”

Setting up my gaming computer in Ubuntu 16.04

This is really a how-to for my personal hardware setup in case I want to try other distributions or operating systems on my gaming computer down the line. However it may be helpful to anyone who would like to play games or run flight sims in a Linux environment. What? Stranger things have happened!

Continue reading “Setting up my gaming computer in Ubuntu 16.04”