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  • Oracle Cloud Infrastructure: using the CLI to manipulate Network Security Groups

    I frequently need to update security rules in one of my Network Security Groups (NSG). Rather than logging into the console and clicking my way through the user interface to eventually change the rule I decided to give it a go and automate the process using the Oracle Cloud Infrastructure (OCI) Command Line Interface (CLI).…

  • Linux BPFtrace: slightly more advanced use cases involving kprobes

    If you look at some of the examples of how to use bpftrace – more specifically how to enable kprobes – you might wonder how to use the tool in more advanced cases. This article was prompted by my research into why biotop as part of the bcc tools initially reported 0 kb read/written on…

  • Deploying I/O intensive workloads in the cloud: don’t fall for the LVM trap

    I have been assessing the “best” storage option for Oracle databases deployed on Infrastructure as a Service (IaaS) VMs quite a few times now. As part of the discussion DBAs often pose the question whether using Linux’s Logical Volume Manager (LVM) is a good choice for data files. It can be, depending on the circumstances…

  • Do you know perf trace? It’s an almost perfect replacement for strace

    Last night while I was working on my POUG 2021 presentation I looked up what’s new with perf(1) since I last spoke about profiling and tracing Linux on-premises and in the cloud back in 2017. Unsurprisingly, quite a few things have changed. A quick warning before we begin As with every tracer/profiler, using tools such…

  • Do I really have to set resource limits for Oracle in systemd unit files?

    TL;DR: it is very much required to set resource limits in systemd unit files. If you’d like to learn more about potential directives to put into a unit file, please have a look at the earlier post I wrote for a more thorough explanation. I also wrote a short post about a potential unit file…

  • Installing perf on Ubuntu 20.04 LTS in Oracle Cloud Infrastructure

    This is a very short post with instructions on how to install perf on Ubunutu 20.04 LTS in Oracle Cloud Infrastructure (OCI). I created my VM using the Canonical-Ubuntu-20.04-Minimal-2021.06.14-0 image. Updating the image first The first thing I do with each image I spin up in the cloud is to update all the packages. By…

  • Using systemd to start an Oracle single instance database when booting

    I don’t work with systemd frequently enough to remember its syntax and other intricacies so I thought I’d just write down how to start an Oracle 19c single instance database via systemd on Oracle Linux 8.4. Primarily so I can look it up later when I need it, but isn’t that the reason many bloggers…

  • Geeking out on Linux: file descriptors and their open modes & flags

    While preparing my talk for the upcoming POUG 2021 conference I wanted to know which flags Oracle passes to open(2) when accessing a data file. A file needs to be opened before its contents can be accessed (no surprises here :). There are quite a few ways of opening a file, depending on whether you…

  • Shell limits, Oracle Single Instance, and systemd in Oracle Linux 8.4

    The more blog posts I write the harder it becomes to come up with a good title. So what is this post all about? In short, it’s about the implications of using systemd to start a single instance Oracle database in Oracle Linux and associated shell limits. In theory this should apply to Single Instance…

  • Automating Vagrant Box versioning

    The longer I work in IT the more I dislike repetitive processes. For example, when updating my Oracle Linux 8 Vagrant Base Box I repeat the same process over and over: Boot the VirtualBox (source) VM Enable port forwarding for SSH SSH to the VM to initiate the update via dnf update -y && reboot…