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Well, if you know you know, otherwise, you could have wasted the whole evening trying to upgrade RHEL 7.9 with High Availability to RHEL 8.x, and failed! If you read this post, head to the link at [1] and you’d see that Red Hat does not support i-place upgrades or rolling-upgrades of cluster nodes from one major release of RHEL to another. Here is an extract from [1]: Red Hat does not support in-place upgrades or rolling-upgrades of cluster nodes from one major release of RHEL to another. For example, there is no supported method for updating some nodes in a cluster from RHEL 6 to RHEL 7, introducing them into the cluster with existing RHEL 6 nodes to take over resources from them, and then updating the remaining RHEL 6 nodes. Upgrades in major releases of RHEL must be done by migrating services from a running cluster on the old release to another cluster running the new release. ...

So, what’s “Here Docs”? Well, if you don’t know what it is yet, then hopefully by the time you finish reading this post you’ll know what it is. Here docs or here documents is a special block code, of which we can use a form of I/O redirection to feed a command list to an interactive program, e.g. cat or the ex text editor according to [1]. Here is an example where a file basic-ingress.yaml was created using here docs. ...

On one of my servers, I used to have a storage device, /dev/sdb, attached to it. That storage was used as an LVM physical volume. It has later been removed, and now I just noticed the following message: [root@banan ~]# lvs Devices file PVID CuDRE3nMN5FMNqYLViHrnE1D7OFDlbX6 last seen on /dev/sdb not found. LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert root almalinux -wi-ao---- <28.40g swap almalinux -wi-ao---- 2.01g Based some research found online, there could be outdated device entries in the device files located in /etc/lvm/devices/system.devices. ...

rustup is a utility used to install and remove rust toolchain. To list the current installed toolchain run: kenno@c2:~$ rustup show Default host: aarch64-unknown-linux-gnu rustup home: /home/kenno/.rustup installed toolchains -------------------- stable-aarch64-unknown-linux-gnu (default) 1.70.0-aarch64-unknown-linux-gnu 1.71.1-aarch64-unknown-linux-gnu 1.72.0-aarch64-unknown-linux-gnu active toolchain ---------------- stable-aarch64-unknown-linux-gnu (default) rustc 1.72.0 (5680fa18f 2023-08-23) To remove a specific version of the toolchain, e.g. 1.70.0-aarch64-unknown-linux-gnu run: kenno@c2:~$ rustup toolchain remove 1.70.0-aarch64-unknown-linux-gnu info: uninstalling toolchain '1.70.0-aarch64-unknown-linux-gnu' info: toolchain '1.70.0-aarch64-unknown-linux-gnu' uninstalled Let’s verify: kenno@c2:~$ rustup show Default host: aarch64-unknown-linux-gnu rustup home: /home/kenno/.rustup installed toolchains -------------------- stable-aarch64-unknown-linux-gnu (default) 1.71.1-aarch64-unknown-linux-gnu 1.72.0-aarch64-unknown-linux-gnu active toolchain ---------------- stable-aarch64-unknown-linux-gnu (default) rustc 1.72.0 (5680fa18f 2023-08-23) To install udpate the new toolchain, run: ...

I have written a hand full of Bash scripts, but none of those utilized array. Why? It’s because of two main things: 1. I don’t know how to use array in Bash, and 2. I would normally switch to write the script in Python instead. Today, however, I need to update an existing script written in Bash to make use of array. This was a perfect excuse for me to spend some 30 minutes to learn about array in Bash. I found a very good tutorial at the following [1]. ...