I have a RHEL 6 Linux cluster setup where the main database storage is replicated on a remote site using DRBD. In case of a failure of the primary site the decision is taken to move operations on the remote site. When the production site is back online sometimes the administrator is too eager to… Read More »
In a Linux HA cluster setup on RHEL 6 that involves replication between sites using DRBD suddenly after reboot of one of the nodes it was imposible to start any cluster service from that node. Surprinsingly there was no issue to do so from the other node. While looking in the /var/log/messages on the affected… Read More »
Sometimes weird things happen when selinux is activated and files are un-tagged or policies are missing. Because I do not want to apply the usual stupid Internet advice: “disable selinux” I am trying to fix it if possible. Two simple steps to alleviate some of the “issues” caused by selinux. STEP 1: Generate SELinux policy… Read More »
The best way to do simple video in Linux is using the command line. This way you can do quick one liner commands that do the job fast and clean. My favourite tool is ffmpeg. Install ffmpeg: If you do not have it already installed to install ffmpeg simply do (in Fedora): Install the rpmfusion… Read More »
Starting with build 1607 finally Windows 10 has a Linux in it. To enable the Linux user space (basically an Ubuntu) the following has to be done: STEP 1: Update Windows to 1607 Make sure you update Windows 10 to a build at least 1607. STEP 2: Activate developer mode Settings -> Updates & security… Read More »
This is a follow-up tutorial on the DRBD replication posts about resynchronization of sites after the failed DR site is recovered. More than a year ago I described in a long tutorial how to use DRBD in a real production environment and the challenges associated to it. See: DRBD based disk replication of a production… Read More »
This is a follow-up tutorial on the DRBD replication posts about resynchronization of sites after the failed PR site is recovered (DRBD split brain recovery). More than a year ago I described in a long tutorial how to use DRBD in a real production environment and the challenges associated to it. See: DRBD based disk… Read More »
This is a follow up tutorial on the DRBD replication posts about promoting the DR site as the main site when PR is failed. More than a year ago I described in a long tutorial how to use DRBD in a real production environment and the challenges associated to it. See: DRBD based disk replication… Read More »
This is a follow up tutorial on the DRBD replication posts about gracious role switching of live sites configured with DRBD replication. More than a year ago I described in a long tutorial how to use DRBD in a real production environment and the challenges associated to it. See: DRBD based disk replication of a… Read More »
Sometimes we need to find specific things in application vast logs, sometimes 10 or 20 rotated logs each hundred of MBs each. For a quick search without using some specialized log viewer we can use the very powerful bash text processing commands. Problem: We have 10 log files each 100MB and we need to find… Read More »