When you repurpose disks from one RAID array to another system, Linux keeps the old RAID metadata intact as a safety measure. This prevents accidental data corruption, but it also blocks you from reusing the disk until the signatures are cleared. RAID metadata isn’t stored in one place — it’s scattered across the disk by…
GRUB2 configuration needs to be regenerated when you modify boot parameters, install new kernels, or adjust default boot entries. The process varies slightly between BIOS and UEFI systems, and between distributions, but follows a consistent pattern once you understand your system layout. Check Your System Firmware Type Before regenerating config, identify whether your system uses…
When writing to disk, you need to know if space is available — especially in systems software, daemons, and critical applications. The POSIX statvfs() call provides filesystem statistics across all POSIX systems, making it more reliable than Linux-specific alternatives like statfs(). The statvfs() API Include the required header: #include <sys/statvfs.h> Function signature: int statvfs(const char…
The /etc/fstab file defines how Linux mounts filesystems at boot and controls mounting behavior for both the system and individual users. Understanding its format and options is essential for reliable storage management. File Format and Fields Each line in /etc/fstab represents one filesystem. Fields are separated by whitespace (tabs or spaces), and lines beginning with…
Sharing internet from a Windows PC to an iPhone via USB is possible but requires careful network configuration. This is less common than tethering the other direction, but useful when you need a stable wired connection without draining your phone’s battery. Prerequisites Windows 10 or Windows 11 iPhone with iOS 12 or later USB-A to…
Shrinking an ext4 filesystem on LVM is riskier than expanding—it requires the filesystem offline and careful size planning. The operation can take hours on large volumes, and mistakes can destroy data. This guide walks through the safe path with verification at each step. Prerequisites Before starting: Backup everything. A full backup of the data being…
The Linux kernel handles video mode configuration through bootloader parameters and kernel graphics drivers. Modern UEFI systems use Kernel Mode Setting (KMS) automatically, but you can override modes when needed. Legacy BIOS systems still use older mechanisms if you’re maintaining older hardware. UEFI Systems: Modern Video Mode Configuration On UEFI systems with GRUB2, add video…
Hadoop 2.x reached end-of-life in 2016. This guide covers setup for learning purposes and legacy system maintenance only. For production deployments, use Hadoop 3.x or later, which includes performance improvements, better YARN scheduling, HDFS erasure coding, and improved security. Cloud-managed options like AWS EMR, Google Dataproc, and Azure HDInsight eliminate most operational overhead. This guide…
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…
Thunderbird wraps lines at 72 characters by default—a sensible standard from the SMTP era, but one that can break formatting when sending code, logs, or plain text that needs to stay on single lines. The fix is straightforward: tell Thunderbird to let the recipient’s client handle line breaking instead. Access the Config Editor Open Preferences…
VMware Player and VirtualBox are two free virtualization platforms that run on Linux hosts. Both offer full virtualization capabilities, though they differ in performance characteristics, ease of use, and licensing models. This guide covers installation, basic operation, and removal on current Fedora releases. VMware Player Install VMware Player Download the installer bundle from VMware’s website….
SSH performance is constrained by cipher choice, especially for large file transfers over high-bandwidth links where CPU becomes the bottleneck. Selecting the right cipher, key exchange algorithm, and compression settings can yield substantial throughput improvements. Current Cipher Landscape Modern OpenSSH (7.4+) has deprecated or removed weak ciphers. Here’s what’s viable today: Secure and performant: chacha20-poly1305@openssh.com…
Vim remains one of the most efficient editors available on Linux and Unix systems. While it has a steep learning curve, the payoff in speed and capability is substantial once you develop muscle memory. This guide covers practical configuration strategies, essential keybindings, and workflow improvements that actually matter in daily use. Setting up your configuration…
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…
Static linking embeds all library code directly into your binary. On Linux, this sounds straightforward but glibc introduces complications that pure static binaries don’t truly exist — the C library still loads dynamic features at runtime like NSS (Name Service Switch), locale data, and character set converters. Understanding these constraints is essential before committing to…
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…
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…
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…