Daily Linux Stuff
More than 30 years ago, when 32 Bit, and Athlon used to be modern, I was fascinated with the little program freq51 (called as xfreq on X11). That thing could use a normal microphone and soundcard, and gave you an idea about the frequency spectrum of arbitrary sounds in real time. Times have changed, Continue reading
When I was looking for a solution that could provide High Availability for two Datacenters, the only solution that remained viable and comprehensible for me was using Corosync/Pacemaker. The reason that I actually need this is, that Mainframe environments typically use two Datacenters, since z/OS can nicely operate with that. The application that I had Continue reading
During my works on Kubernetes on Linux on Z and the creation of https://github.com/azouhr/pgtwin, I came across the same issue that most admins have to solve in two-node clusters. How can I get quorum, and what node is to be the primary. While using additional techniques like providing a second corosync ring for HA, and even Continue reading
in the previous blog pgtwin — HA PostgreSQL: VM Preparation we setup two VMs with KVM to prepare for a HA PostgreSQL setup. Now, we will configure the Corosync cluster engine, prepare PostgreSQL for synchronous streaming replication and finally configure Pacemaker to provide high availability. Configure Corosync Corosync has its main configuration file located at /etc/corosync/corosync.conf .…
In my last post Kubernetes on Linux on Z, I explained why I need a highly available PostgreSQL Database to operate K3s. Of course, a HA PostgreSQL that works with just two Datacenters has lots more usecases. Let me explain how to perform an initial setup like the one that I use for development. Preparation of Continue reading
This year, I had the task of setting up a Kubernetes environment on a Linux Partition on a s390x system. At first sight, this sounds easy, there are offerings out there that you can purchase. The second look however can make you wonder. There is a structural mismatch between typical Linux on Z environments and Continue reading
How to quickly build a s390x development environment on your local workstation. Continue reading
Using Port Forwarding with xinetd has served me well at many occasions. As time proceeds, new technologies show up that allow for similar functionality and others are deprecated. When reading about the obsoletion of xinetd in SLES15, I wondered if you could do the port forwarding also with systemd instead of xinetd. To accomplish the Continue reading
Virtualization systems like KVM, Xen, or z/VM offer the possibility to move running guests from one physical server to another one without service interruption. This is a cool feature for the system administrator because he can service a virtualization host without shutting down any workload on his cluster. Before doing such a migration, the system Continue reading
The standard method to access z/VM is using a 3215 terminal with a terminal emulator. With linux, the x3270 package provides a free emulator for these terminals. One of the features of z/VM is, that you can define several consoles for a guest. This is very helpful if there are problems with a guest that Continue reading