Polipo: Easy Transparent proxy

When your server numbers grow and you have clusters you want to upgrade all at one time, you will probably want some kind of proxy that will cache stuff for you. Upgrading cluster of hadoop with like 10 servers, can take up to 2hours just to download packages to all nodes, since Cloudera limits bandwidth

Vyatta / VyOS: site-to-site OpenVPN + Open Shortest Path First (OSPF) setup

When you scale your network from one location to another, sooner or later you may want to merge those networks and have only one. To merge networks, you need to setup 2 routers and site-to-site connection between them. One of open source solutions is OpenVPN and Vyatta/VyOS. This article will cover setting up site-to-site connection

Migrating MongoDB databases

MongoDB (from “humongous”) is a scalable, high-performance, open source NoSQL database. Written in C++. A while ago I had to move some servers with MongoDB replica set from our current colocation to new provider Hetzner. There are few different ways to get this done: Get one member of replica set removed, create new MongoDB server

Creating, extending and shrinking logical volumes (LVM)

In earlier post I explained how to copy logical volumes over network, but I didn’t actually explain how to create LV’s and why exactly use them at all.  Few benefits of using LVM over old partitioning system: Spanning logical volume over many physical volumes, even if they reside on different physical disks (which isn’t really

Leap second, Java and NTP leads to disaster – how to setup ntpd to avoid that

Like many other companies around the globe we also had some issues with last leap second. We couldn’t figure out why is our hadoop cluster acting strangely and using almost all CPU. After a while of browsing we found out, that the real cause of this was Java and leap second. As you may know