Finding Bad Blocks on Linux Storage Devices If you suspect a disk has bad blocks, use the badblocks utility to scan for them. This tool probes a device (usually a disk partition) and reports which blocks are unreliable or unreadable. Basic Usage badblocks /dev/sda1 This scans /dev/sda1 from the first block to the last block…
Installing MATE on Fedora 41 MATE is a continuation of GNOME 2, maintained by the MATE Desktop Environment project. It’s included in Fedora’s official repositories and is a supported desktop option. Install MATE Desktop MATE is available as a desktop environment group in Fedora 41’s repositories. Install the base desktop with: sudo dnf install @mate-desktop…
Testing connectivity between Linux hosts When you need to verify that two Linux systems can communicate over a specific protocol and port, you have several solid options. Let’s cover the most practical approaches. Using nc (netcat) The nc command remains a reliable choice for quick connectivity tests. It’s widely available and requires no special setup….
LVM Fundamentals LVM (Logical Volume Management) abstracts physical storage into logical volumes, giving you flexibility to resize filesystems, snapshot data, and manage disk space without downtime. It sits between your physical disks and the filesystems you mount. The three core LVM concepts are: Physical Volumes (PVs): Physical disks or disk partitions Volume Groups (VGs): Collections…
Finding Hard Links to a File A hard link is an additional directory entry pointing to the same inode as the original file. Unlike symbolic links, hard links share the same inode number and have identical permissions, ownership, and content. To find all hard links to a file, you need to locate every directory entry…
Using MAP_NORESERVE for Oversized Memory Mappings When you mmap() a range larger than your system’s total physical memory plus swap, the kernel normally reserves swap space to back the mapping. If that reservation would exceed available swap, mmap() fails with ENOMEM. The MAP_NORESERVE flag lets you bypass this reservation requirement. Understanding the Default Behavior By…
Evolution Data and Configuration Locations on Linux Evolution is a full-featured personal information management suite that handles email, contacts, calendars, and tasks. It includes enterprise features like native Microsoft Exchange support and integrates deeply with GNOME’s ecosystem. To troubleshoot issues, migrate data, back up configurations, or secure your setup, you need to know where Evolution…
NFSv4 Port Forwarding and External Network Access NFSv4 significantly simplifies network exposure compared to NFSv3. Where NFSv3 requires managing multiple dynamic ports (mountd, statd, lockd), NFSv4 uses only port 111 (rpcbind) and port 2049 (NFS). This makes firewall configuration and port forwarding straightforward. For production environments, consider implementing Kerberos authentication (krb5, krb5i, or krb5p) instead…
Adding Custom Fields to Receipts in Dynamics 365 Commerce When you need to display data on point-of-sale receipts that isn’t available in the standard receipt designer, you’ll need to create a custom field. This involves work in both Dynamics 365 (the backend) and the Retail SDK (the POS application layer). This walkthrough covers adding a…
.NET Core 2.1: What Actually Shipped This post covers .NET Core 2.1, which released in May 2018. Some of the predicted features below didn’t materialize as described; we’ll clarify what actually landed versus what was speculated. What is .NET Core? .NET Core is Microsoft’s open-source, cross-platform runtime for building applications in C#, F#, and Visual…
Connecting to Linux from Windows If you’re forced to use Windows but need to interact with Linux systems, you’ll need remote access tools. SSH is the standard—it’s secure, scriptable, and works everywhere. SSH clients: PuTTY: Simple GUI SSH client. Handles key authentication, serial connections, and X11 forwarding. Windows Terminal: Built into Windows 11, integrates OpenSSH…
Hibernate Envers Overview Hibernate Envers is an auditing and versioning framework built on top of Hibernate/JPA. It automatically tracks entity changes without requiring manual logging or version management code. Key capabilities: Audits all JPA-specified mappings plus Hibernate-specific extensions Tracks changes per transaction using revision entities Stores audit data in separate tables with customizable naming Queries…
Deploying ASP.NET Core MVC Applications to Azure Web Apps ASP.NET Core remains one of the most efficient frameworks for building scalable web applications. This guide walks through deploying an ASP.NET Core MVC application to Azure Web Apps using Visual Studio — the quickest path from local development to production. Prerequisites You’ll need: An active Azure…
Assembly Syntax: AT&T vs Intel Before diving into instruction encoding, you need to understand the two assembly syntaxes you’ll encounter in documentation and tools. Intel syntax (used in Intel/AMD manuals) and AT&T syntax (default in GNU toolchains on Linux) differ fundamentally in operand order: Intel syntax: dest, source — e.g., add r8, [rdi+0xa] AT&T syntax:…
Forcing HDFS Metadata Checkpointing The Secondary NameNode periodically merges the fsimage and edits log files to keep the edits log size manageable and consolidate metadata. When this checkpointing fails, you may see errors like: ERROR org.apache.hadoop.hdfs.server.namenode.SecondaryNameNode: Exception in doCheckpoint java.io.IOException: Inconsistent checkpoint fields. This typically indicates a mismatch between the NameNode and Secondary NameNode metadata…
Kernel Debugging with Module Parameters When you need to debug kernel behavior without building full instrumentation frameworks, module parameters offer a pragmatic shortcut. Rather than reaching for perf, kprobes, or eBPF immediately, you can add simple toggles and state tracking directly in the code you’re investigating, then control them at runtime through sysfs. Why This…
TAP Devices with QEMU/KVM QEMU/KVM networking uses several layers to move packets between host and guest. Understanding this stack helps when debugging connectivity issues or optimizing performance. Basic TAP Setup A typical QEMU/KVM VM using TAP networking and VirtIO looks like this: sudo qemu-system-x86_64 \ -name myvm \ -machine pc,accel=kvm \ -m 2048 \ -smp…
Measuring Task I/O Utilization with eBPF: Microsecond Accuracy Most popular task monitoring tools (top, iotop, procfs) can only sample disk I/O information at granularity limited by kernel timer frequency—typically once per second. This sampling rate misses short-lived I/O bursts and makes it difficult to accurately measure which tasks are truly I/O bound. This post explains…
Common On-Page SEO Mistakes Costing You Rankings Google’s search algorithms have become significantly more sophisticated. What passed for acceptable SEO a decade ago—keyword stuffing, aggressive link manipulation, deceptive tactics—now triggers manual penalties or algorithmic demotions. If you’re managing websites, understanding these mistakes can prevent serious ranking damage. Misusing nofollow Tags Many site owners incorrectly use…
Understanding SEO Timeline and Effort SEO is not quick. This is the reality that catches most people off guard. The internet has conditioned us to expect instant results — viral content, overnight success, algorithmic magic that transforms a website in weeks. None of that applies to SEO. Let’s be direct about expectations: a newly published…