linux Archive

Creating bootable Windows USB from Linux

Intro Many of you probably have Linux for your desktop OS and therefore don’t have access to Microsoft’s DVD/USB tool that creates bootable USB from iso. I’ve had few issues in the past when I tried to make bootable USB from my windows.iso file. Pretty lame, but still… There used to be programs like winusb

Lack of linux kernel entropy – Example how things can go wrong

The issue Lately we’ve been experimenting with puppet and setting up our frontend webservers with it. Our junior sysadmin was setting up things on a server that already had frontend database virtualized and everything was going smoothly, to the part, when he had to setup whole webserver from scratch. I was working with Percona’s XtraDB MySQL Cluster in

Loadbalancing / failover with IPVS and keepalived

Introduction Correct failover and loadbalancing is crucial for high availablility environment. With proper setup we can eliminate single points of failure in case of server crash. I use linux kernel’s support for load balancing, since that seems as well documented and scalable method. What I want to achieve here, is actually fully redundant architecture, so

Checking limits of a running Linux process – ulimit

If we are dealing with servers that need to handle a lot of concurrent connections, we soon bump limits of our default Linux server installation. In order to be able to further modify these limits, Linux has ulimit. We can set system wide limits on CentOS inĀ /etc/security/limits.conf or manually setting them with ulimit command. We

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