Switching user (sudo)

On any Linux system, there is only one account with all the super-administrator power, this is the root account, the account with ID 0.
It is not recommended to use directly this account, for different reasons, all linked to security and traceability:
  • If allowed to be used to log on, one half of the job is done for the hackers, they just need to find the password as the username is always the same to get super power on the system

Running Linux on Windows with Vagrant

Testing Linux software on Windows with Vagrant

There is no magic, you will not able to run a Linux software natively on Windows without third-parties addon.

But thanks to a lot of vendor, you have virtualization tools available for doing your tests.
Everything that has been tested and presented on this site, if not done directly on physical Linux host, has been done with the help of a virtualization software.
Even if your host OS is Linux, there are advantages to use the virtualization:
  •  you can use different version of your distribution

Ceph and GlusterFS comparison

GlusterFS and Ceph are both a software defined storage solution, parts of the RedHat solutions portfolio.
If at first view they can seem to be identical in what they offer (storage distributed on commodity hardware, with fault-resilience), when looking more in depth, there are some difference that can make one of the two solutions better for some use cases than the other, and vice-versa.

So, let's dig into what these 2 solutions have to offer:


Ceph Block Device usage

We saw previously the steps to follow to have a Ceph cluster up and running, with some distributed and protected storage.
Now, it is time to add some services on it to let your applications, VM or servers to access and use this storage.
We will add a block device, a Ceph filesystem and an Object gateway (compatible with OpenStack Swift and Amazon S3)

GFS on iSCSI shared storage

This method, based on software version delivered with CentOS 6.0 use dlm_controld.pcmk and gfs_controld.pcmk, which are special version developped to be used directly by Pacemaker. After upgrading the OS to CentOS 6.2, the RPM providing dlm_controld.pcmk and gfs_controld.pcmk were replaced by cman, wichi provides the standard gfs_controld and dlm_controld. To be use these two with Pacemaker, we need to enable CMAN with Corosync.