Openvswitch RPM build on Centos 7

If you ever needed to build openvswitch for Centos 7 (including kernel module) this post may help you. Commands to build a RPM: Download openvswitch source. I've tested with 2.7.x and 2.9.x series. So I recommend you to do the same. It can be found at (if link becomes absolute look for a newer one, … Continue reading Openvswitch RPM build on Centos 7 →

cd Between Last Two Directories – A Quick Method

if you need to change your previous directory rapidly you can add - (dash) to your cd command and no more arguments. For instance: if you were in: /etc/apt/sources.list.d/ and now in: /home/myuser you can easily go back to /etc/apt/sources.list.d/ with the command cd -

System Sleep States

When you put your computer to suspend, it will turn some of its devices to power saving mode to preserve energy consumption. But computers have many sleep states from deeper to shallow just like humans. The most shallow one is the freeze (or S0-idle) which only puts CPU to idle and if possible turn other … Continue reading System Sleep States →

SysReq, Raising Elephants Is So Utterly Boring

SysRq keyboard key is very magical. You can perform a safe reboot a locked up computer with this key. To achieve this remember mnemonics: "Raising Elephants Is So Utterly Boring" To use SysRq: Press Alt and SysRq (Print Screen) keys at the same time (but do NOT release them) While holding Alt and SysRq keys … Continue reading SysReq, Raising Elephants Is So Utterly Boring →

Reclaim empty space from, Shrink disk of qcow2 disk file

To reclaim disk space (in other words to shrink disk space) of qcow2 disk file you need to run following steps. 1. Fill guest disk with empty file This is required since disk does not really hold its configured size, instead it has a sparse file format in creation time. After a while disk gets … Continue reading Reclaim empty space from, Shrink disk of qcow2 disk file →