https://nalar.dev/tags/filesystem/ Recent content in Filesystem 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, copied: false }" class="code-block group relative my-6 overflow-hidden rounded-xl border border-line bg-surface-muted dark:border-night-line dark:bg-night-surface"> <button type="button" @click="navigator.clipboard.writeText(code); copied = true; setTimeout(() => copied = false, 1600)" class="absolute right-3 top-3 z-10 rounded-lg border border-line-strong bg-surface px-2 py-1 font-mono text-[0.65rem] text-muted opacity-0 transition group-hover:opacity-100 hover:bg-ink hover:text-white dark:border-night-line dark:bg-night dark:text-night-muted dark:hover:bg-white dark:hover:text-ink"> <span x-text="copied ? 'Copied' : 'Copy'"></span> </button> <div class="overflow-x-auto p-4 text-sm leading-6 [&_pre]:!m-0 [&_pre]:!bg-transparent [&_pre]:!p-0 [&_code]:font-mono"> <div class="highlight"><pre tabindex="0" style="background-color:#fff;-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> </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>