https://nalar.dev/tags/troubleshooting/ Recent content in Troubleshooting on Nalar Hugo en-us Tue, 01 Sep 2026 00:00:00 +0700 https://nalar.dev/find-hidden-disk-usage-with-df-du-and-lsof/ Tue, 01 Sep 2026 00:00:00 +0700 https://nalar.dev/find-hidden-disk-usage-with-df-du-and-lsof/ <p>A Linux filesystem can report 95% usage in <code>df</code> while <code>du</code> appears to account for much less. The tools are not contradicting each other: they measure different things.</p> <p><code>df</code> asks the filesystem about allocated blocks. <code>du</code> walks visible directory entries and sums blocks reachable through those paths. The gap between those views points to several useful troubleshooting cases.</p> <h2 id="start-with-the-filesystem-view">Start with the filesystem view</h2> <p>Check filesystems and their types:</p> <div x-data="{ code: $el.querySelector('code').innerText }" class="relative my-4 rounded-lg group" > <button @click="navigator.clipboard.writeText(code); $el.innerText = 'Copied!'; setTimeout(() => $el.innerText = 'Copy', 2000)" class="absolute top-2 right-2 bg-neutral-700 text-white text-xs px-2 py-1 rounded opacity-0 group-hover:opacity-100 transition-opacity" > Copy </button> <div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash"><span style="display:flex;"><span>df -hT</span></span></code></pre></div> </div> <p>Identify the mount that is actually full. Do not immediately scan recursively from <code>/</code>; container mounts, network filesystems, and bind mounts can make that slow and misleading.</p> https://nalar.dev/linux-network-troubleshooting-ip-ss-dig-curl/ Tue, 01 Sep 2026 00:00:00 +0700 https://nalar.dev/linux-network-troubleshooting-ip-ss-dig-curl/ <p>When a Linux service is &ldquo;unreachable,&rdquo; the failure can be in several different layers: the local interface, routing, a listening socket, DNS, a firewall, TLS, or the application itself.</p> <p>Randomly restarting services makes diagnosis harder. A better approach is to move from local state outward and identify the first layer that does not behave as expected.</p> <h2 id="1-confirm-the-interface-and-address">1. Confirm the interface and address</h2> <p>Start with the addresses configured on the host:</p>