Author Archive

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

Moving logical volume (LVM) over network

Sometimes you come to an issue of moving raw volume from one server to another. Now this can be pretty complicated thing. You could make a snapshot of LV or make an image file, which you would copy then to another server, but that takes ages. When creating image you also need almost double the