Category Archives: Linux

A+ Security for WordPress Blog – HTTP Strict Transport Security

By | February 9, 2017

Keeping the installation of your own WordPress blog highly secure is very important. In today’s fast pace discovery of security vulnerabilities you must keep an eye on all the new security threats and update as soon as possible the security to try to cover the new threat. An invaluable tool is the security test from… Read More »

RedHat/Fedora Linux NIC bonding

By | February 9, 2017

Red Hat Enterprise Linux allows administrators to bind multiple network interfaces together into a single channel using the bonding kernel module and a special network interface called a channel bonding interface. Channel bonding enables two or more network interfaces to act as one, simultaneously increasing the bandwidth and providing redundancy. The behaviour of the bonded… Read More »

#DRBD based disk replication of a production cluster to a remote site cluster on RHEL 6

By | May 26, 2017

1 General Considerations Our example enterprise applications run on a Linux Cluster with a shared cluster storage resource. Having this HA setup ensures that we have a high rate of service availability on the production site. To ensure that the disruption time in service of our enterprise application is minimal as possible the best solution… Read More »

iSCSI SAN resources configuration as shared disks in a cluster environment, replicated also with DRBD

By | April 24, 2017

The following configuration was created to use the iSCSI exported resources from a NetApp storage device as shared disk resources in a Linux cluster environment. The same resources are also replicated to a remote cluster using DRBD disk replication. The production environment contains four exported SAN resources which will be used as shared resources in… Read More »

Fedora Linux: LVM Single Drive to LVM RAID 1 Mirror Migration

By | March 3, 2017

All started when I wanted to have a true HA configuration for the server nodes. That implies that not only the storage of each server is a RAID10 setup, but also the boot and root resources are in a RAID1 configuration. I started to use an old and known tutorial to convert from standard installation… Read More »

Relax and Recover with bareos

By | June 30, 2015

A good way to backup the OS of the servers is to use rear Relax and Recover. Following are the steps to ensure that we have a proper rescue data set for both servers. STEP 1: Install rear from the Fedora repo on both nas1 and nas2 [root@nas1 ~]# dnf install rear [root@nas2 ~]# dnf… Read More »

Manipulate PDFs with gostscript

By | June 28, 2015

Basic Usage Convert PostScript to PDF: gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile=fileout.pdf filein.ps Merge/combine PDF and/or PostScript files: gs -q -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -sOutputFile=fileout.pdf \ filein.ps filein2.pdf Extract a page from a PostScript or a PDF document: gs -q -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -dFirstPage=3 -dLastPage=3 \ -sOutputFile=fileout.pdf filein.ps Additional Options PDF optimization level selection… Read More »

Linux command line tips 1

By | July 13, 2015

The Linux command line environment is very powerful and full of very useful command line instructions that are ignored by a lot o people. Following are some of the discovered commands I find very usefull: The “ls like” group: List all the usb devices: [root@localhost ~]# lsusb Bus 004 Device 002: ID 8087:0024 Intel Corp.… Read More »

USB Wireless interface on Fedora Linux

By | February 9, 2017

I am planning to deploy a test openStack infrastructure, “Minimal architecture example with legacy networking (nova-network)”, on the 2 x Hp MicroServer Gen 8 setup from my home data centre. The nova-network architecture needs at least two nodes and on each node a minimal of two network interfaces must be available. The HP MicroServers have… Read More »

Convert an existing 2 disk RAID 1 to a 4 disk RAID 10

By | December 7, 2015

When you want to have a secure set-up for your data storage having only two disks available a LVM over a RAID 1 set-up looks like the best solution. When an upgrade is necessary then having two separate RAID 1 based LVMs is no longer so appealing. To keep the same reliability of a disk… Read More »