LVM abstracts physical storage into logical volumes, letting you resize filesystems online, add drives transparently, and manage capacity without downtime. This guide covers the most common task: extending a mounted ext4 filesystem when you need more space. Prerequisites Online extension requires the resize_inode option enabled on your ext4 filesystem. Check this first: tune2fs -l /dev/vg/lv_home…
Emacs keybindings rely heavily on Ctrl because the editor was designed for Lisp machines in the 1970s—machines where Ctrl sat near the spacebar. Modern PC keyboards moved it to the corner, making constant reaches painful. Once millions of users built muscle memory around these bindings, changing them became impractical. If modern keyboard ergonomics matter to…
A file-backed VBD stores the entire VM disk in a single file on the Dom0 filesystem. This approach works well for testing and development, though LVM-backed or disk-backed storage provides better performance for production workloads. Create a working directory and a 20GB sparse file-backed VBD: mkdir -p /home/xen/f41install cd /home/xen/f41install dd if=/dev/zero of=./vmdisk0 bs=1k seek=20480k…
Xen remains a production-grade hypervisor used by major cloud providers like AWS and Citrix, though KVM has become the default for most Linux distributions. This guide covers setting up Xen Domain-0 (the privileged management domain) on modern Fedora systems. Installing Xen Packages Install the required Xen packages: sudo dnf install xen xen-libs xen-runtime xen-dom0-tools Modern…
Fedora’s default font rendering works but benefits significantly from installing current font versions and tuning fontconfig. This guide covers practical font configuration using only free software and fonts available in standard repositories. Installing fonts Fedora ships with Liberation fonts, but ensuring you have version 2.x (which renders substantially better than 1.x) is the first step….
Programs need to shut down gracefully—saving state, closing connections, flushing buffers—rather than terminating abruptly. A daemon might receive a termination signal and need to persist in-memory data before exiting. The challenge is catching these signals in C and responding appropriately. Signal basics The kill command sends SIGTERM by default. This signal is catchable and allows…
Benchmarks exist to answer one question: how fast can this system process data? The AMPLab Big Data Benchmark, developed by UC Berkeley, became a foundational effort to answer that question systematically across different distributed query engines. The Benchmark’s Original Scope The AMPLab benchmark evaluated five systems circa 2013: Redshift – Amazon’s columnar data warehouse (built…
Choosing the right cloud storage service requires understanding how each platform handles data consistency. This post covers the current consistency guarantees from the three major providers and how they affect your application design. Amazon S3 S3 is a key-based object store built for Internet-scale workloads. The consistency model is now straightforward across all operations. S3…
Vim’s default OCaml indentation is mediocre at best. The ocp-indent tool provides intelligent, syntax-aware indentation that respects OCaml conventions and integrates cleanly with Vim and Neovim. Installing ocp-indent Install via opam: opam install ocp-indent This installs the indentation engine and Vim plugin support. Verify the installation: which ocp-indent Configuring Vim Add this to your ~/.vimrc…
SSH port forwarding lets you tunnel network traffic through an encrypted connection, making it essential for accessing services on restricted networks, exposing local services safely, or routing traffic through a jump host. This guide covers the three main types and production-ready practices. Local Forwarding Local forwarding listens on your local machine and relays connections through…
Xen remains in production use at scale across AWS EC2, Citrix Hypervisor, and various cloud providers, though KVM has become the default hypervisor for most Linux distributions. If you’re operating a Xen environment, Dom0 resource management is critical to system stability. Why Dom0 Resource Management Matters Dom0 performance directly affects your entire virtualized infrastructure. Since…
This guide sets up OpenLDAP for centralized authentication and NFS with automount to provide unified home directories across a cluster. The setup uses modern OpenLDAP backends and current NFS4 best practices. System Environment Server: LDAP and NFS: 10.0.0.2, Fedora 41 x86_64 Base DN: dc=lgcpu1 Clients: Range: 10.0.0.1/24, Fedora 41 x86_64 LDAP Server Setup Package Installation…
UDP (User Datagram Protocol) defined in RFC 768 provides a lightweight alternative to TCP. Unlike TCP’s stream-oriented approach, UDP delivers discrete packets — each recvfrom() or recvmsg() call returns one complete datagram. The tradeoff is real: you gain speed and lower overhead, but lose automatic reliability guarantees. Your application must handle packet loss, reordering, and…
Measuring time accurately matters for performance profiling, benchmarking, and latency-sensitive applications. Linux provides several APIs with different tradeoffs in resolution, overhead, and reliability. Understanding which to use prevents subtle bugs in production code. POSIX Time APIs: gettimeofday and clock_gettime gettimeofday() and clock_gettime() are the standard POSIX calls for reading system time. gettimeofday() returns seconds and…
John Ousterhout, a professor of computer science at Stanford, maintains a collection of “Favorite Sayings” grounded in decades of building real systems—RAMCloud, Tcl, and extensive work in distributed systems. These aren’t abstract principles. They’re lessons that apply directly to the work of building, debugging, and shipping software at scale. Optimize After Measurement, Not Before The…
Ubuntu locks the root account by default as a safety measure—it prevents accidental system damage and enforces audit trails through sudo. If you genuinely need direct root access, here’s how to enable it and the security tradeoffs involved. Set a root password The simplest approach: sudo passwd root You’ll be prompted to enter and confirm…
iOS doesn’t expose SOCKS proxy settings in the Settings UI, but it supports Proxy Auto-Config (PAC) files natively. This lets you route iOS traffic through an SSH tunnel on a Linux/Unix host without installing a VPN app. Prerequisites iOS device (iPhone/iPad) on WiFi Linux/Unix host (same network or internet-accessible) with SSH access Web server to…
MediaWiki stores its main page configuration in the MediaWiki:Mainpage system message. By default, this points to “Main Page”, but you can change it to any title that suits your wiki’s purpose. This process involves updating the system message, creating your new homepage, and handling redirects properly to avoid breaking external links and SEO. Step 1:…
MediaWiki’s sidebar is managed through the MediaWiki:Sidebar special page, a simple text-based system that controls navigation for your entire wiki. Changes take effect immediately across all pages. Accessing the Sidebar Configuration Navigate to the sidebar editor using one of these methods: Direct URL (replace example.com with your domain): With pretty URLs: https://example.com/w/MediaWiki:Sidebar Without pretty URLs:…
rclone is the modern standard for mounting Google Drive on Linux — it’s actively maintained, handles authentication reliably, and works across distributions without compilation. Install rclone Most distributions package rclone. Install via your package manager: # Debian/Ubuntu sudo apt install rclone # Fedora/RHEL sudo dnf install rclone # Arch sudo pacman -S rclone Or install…