From 44d34874025359ddd48557a50a873199813212c5 Mon Sep 17 00:00:00 2001
From: FosterStack Admin <317177128+fosterstack-admin@users.noreply.github.com>
Date: Thu, 8 Oct 2026 20:22:38 -0400
Subject: [PATCH] Page: how big a server does a build cache need

---
 build-cache-server-sizing/index.html | 131 +++++++++++++++++++++++++++
 sitemap.xml                          |   4 +
 2 files changed, 135 insertions(+)
 create mode 100644 build-cache-server-sizing/index.html

diff --git a/build-cache-server-sizing/index.html b/build-cache-server-sizing/index.html
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+<!doctype html>
+<html lang="en">
+<head>
+<meta charset="utf-8">
+<meta name="viewport" content="width=device-width, initial-scale=1">
+<title>How big a server does a build cache need? CPU, RAM and disk</title>
+<meta name="description" content="Starting sizes for a self-hosted Gradle and Maven build cache server: CPU, RAM and disk, how to set the size cap in bytes, and two mistakes that make it look useless.">
+<link rel="canonical" href="https://fosterstack.com/build-cache-server-sizing/">
+<link rel="icon" href="/favicon.svg" type="image/svg+xml">
+<link rel="icon" href="/favicon.ico" sizes="any">
+<link rel="apple-touch-icon" href="/apple-touch-icon.png">
+<style>
+  :root {
+    --bg: #ffffff; --fg: #16181d; --muted: #5b6472; --line: #e4e7ec;
+    --accent: #0d7a5f; --accent-fg: #ffffff; --card: #f6f8f9; --warn-bg: #fff7ed; --warn-line: #fdba74;
+    --mark: #0f4d66;
+  }
+  @media (prefers-color-scheme: dark) {
+    :root {
+      --bg: #101318; --fg: #e8eaf0; --muted: #98a2b3; --line: #262c36;
+      --accent: #2fbf95; --accent-fg: #08110e; --card: #171c23; --warn-bg: #241a10; --warn-line: #7c4a12;
+      --mark: #e8eaf0;
+    }
+  }
+  * { margin: 0; padding: 0; box-sizing: border-box; }
+  body {
+    background: var(--bg); color: var(--fg);
+    font: 16px/1.6 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
+    -webkit-font-smoothing: antialiased;
+  }
+  main { max-width: 44rem; margin: 0 auto; padding: 0 1.25rem 4rem; }
+  header.site { max-width: 44rem; margin: 0 auto; padding: 1.25rem; display: flex; align-items: baseline; gap: .6rem; }
+  .logo { font-weight: 700; font-size: 1.05rem; letter-spacing: -.01em; }
+  .logo span { color: var(--accent); }
+  .logo .mark { width: 1.2em; height: 1.2em; vertical-align: -.24em; margin-right: .4em; }
+  .tag { color: var(--muted); font-size: .85rem; }
+  .notice {
+    background: var(--warn-bg); border: 1px solid var(--warn-line); border-radius: 8px;
+    padding: .7rem 1rem; font-size: .92rem; margin: 1.5rem 0 2.5rem;
+  }
+  h1 { font-size: 2rem; line-height: 1.2; letter-spacing: -.02em; margin-bottom: 1rem; }
+  .lede { font-size: 1.12rem; color: var(--muted); margin-bottom: 2rem; }
+  h2 { font-size: 1.25rem; margin: 3rem 0 .9rem; letter-spacing: -.01em; }
+  p + p { margin-top: .8rem; }
+  .cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr)); gap: .8rem; margin-top: 1rem; }
+  .card { background: var(--card); border: 1px solid var(--line); border-radius: 10px; padding: 1rem 1.1rem; }
+  .card h3 { font-size: .98rem; margin-bottom: .35rem; }
+  .card p { font-size: .9rem; color: var(--muted); }
+  ul.trust { list-style: none; margin-top: .5rem; }
+  ul.trust li { padding: .45rem 0 .45rem 1.6rem; position: relative; }
+  ul.trust li::before { content: "✓"; position: absolute; left: .2rem; color: var(--accent); font-weight: 700; }
+  code, pre { font-family: ui-monospace, "SF Mono", Menlo, monospace; font-size: .88em; }
+  code { background: var(--card); border: 1px solid var(--line); border-radius: 5px; padding: .1em .35em; }
+  pre code { background: none; border: 0; padding: 0; color: inherit; font-size: 1em; }
+  button {
+    padding: .7rem 1.3rem; font-size: 1rem; font-weight: 600; cursor: pointer;
+    background: var(--accent); color: var(--accent-fg); border: 0; border-radius: 8px;
+  }
+  button:disabled { opacity: .6; cursor: default; }
+  table { width: 100%; border-collapse: collapse; font-size: .92rem; margin-top: 1rem; }
+  th, td { text-align: left; padding: .55rem .6rem; border-bottom: 1px solid var(--line); vertical-align: top; }
+  th { font-size: .8rem; text-transform: uppercase; letter-spacing: .04em; color: var(--muted); }
+  pre { background: #0f172a; color: #e2e8f0; padding: .9rem 1rem; border-radius: 8px;
+        overflow-x: auto; font-size: .9rem; line-height: 1.5; }
+  .cta-row { display: flex; gap: .6rem; flex-wrap: wrap; margin-top: 1.1rem; }
+  .btn { display: inline-block; padding: .55rem 1rem; border-radius: 8px; font-weight: 600;
+         text-decoration: none; background: var(--accent); color: #fff; }
+  .btn-secondary { background: transparent; color: inherit; border: 1px solid #cbd5e1; }
+  .muted-note { color: var(--muted); font-size: .93rem; margin-top: 1.1rem; }
+  footer { border-top: 1px solid var(--line); margin-top: 4rem; padding: 1.5rem 1.25rem 3rem; }
+  footer div { max-width: 44rem; margin: 0 auto; color: var(--muted); font-size: .82rem; }
+  a { color: var(--accent); }
+</style>
+</head>
+<body>
+<header class="site">
+  <div class="logo"><svg class="mark" viewBox="0 0 96 96" aria-hidden="true" focusable="false"><rect x="12" y="14" width="72" height="18" rx="5" fill="var(--mark)"/><rect x="12" y="39" width="48" height="18" rx="5" fill="var(--mark)"/><rect x="12" y="64" width="26" height="18" rx="5" fill="var(--accent)"/></svg>foster<span>stack</span></div>
+  <div class="tag">Infrastructure worth keeping — and kept patched.</div>
+</header>
+<main>
+  <h1>How big a server does a build cache need? CPU, RAM and disk</h1>
+  <p class="lede">You are sizing a disk, not a compute tier. The server is one small program that idles in tens of megabytes, so the question is how much cache you want to keep.</p>
+
+  <h2>Starting sizes</h2>
+  <table>
+    <tr><th></th><th>vCPU</th><th>RAM</th><th>Disk</th></tr>
+    <tr><td>Absolute minimum</td><td>1</td><td>1 GB</td><td>cache cap + about 5 GB for the system</td></tr>
+    <tr><td>Recommended start, about 5 to 20 developers plus CI</td><td>1 to 2</td><td>2 GB</td><td>25 to 50 GB SSD</td></tr>
+    <tr><td>Larger CI farms</td><td>2 to 4</td><td>4 to 8 GB</td><td>cache cap + about 20%</td></tr>
+  </table>
+  <p class="muted-note">These are starting points from our deployment guide. Your build graph decides the rest. It is hard to be limited by CPU, because the busy path is reading and writing stored files, not computing.</p>
+
+  <h2>Set a size cap</h2>
+  <p>Choose how much cache you want, set it with <code>FSCACHE_MAX_BYTES</code>, and make the disk about 20% bigger. When the cache reaches the cap it removes the least recently used entries and never grows past it. The extra room covers file system overhead and uploads in progress.</p>
+  <p><strong>The value is in bytes.</strong> It is easy to be wrong by a factor of 1024, so copy one:</p>
+  <table>
+    <tr><th>Cap</th><th><code>FSCACHE_MAX_BYTES</code></th></tr>
+    <tr><td>10 GiB</td><td><code>10737418240</code></td></tr>
+    <tr><td>20 GiB</td><td><code>21474836480</code></td></tr>
+    <tr><td>50 GiB</td><td><code>53687091200</code></td></tr>
+    <tr><td>100 GiB</td><td><code>107374182400</code></td></tr>
+  </table>
+
+  <h2>Two mistakes that look like "the cache doesn't help"</h2>
+  <ul class="trust">
+    <li>A cap that is far too small, such as 20 MiB when you meant 20 GiB, makes it evict constantly, so the hit rate never climbs. The status page at <code>/statusz</code> shows the cap it read next to current usage.</li>
+    <li>Leaving the cap at its default of 0, which means no limit, on a small disk is the one setup that will fill the disk.</li>
+  </ul>
+
+  <h2>Put it near the runners</h2>
+  <p>On bigger setups the network matters more than the processor. A small server in the same region, ideally the same network, as your CI runners beats a large one far away.</p>
+
+  <p class="muted-note">Related: <a href="/migrate-build-cache-node/">Gradle and Maven setup</a> and <a href="/jenkins-ci-build-cache/">Jenkins and CI build cache</a>. Full detail is in the <a href="https://github.com/fosterstack/cache/blob/main/docs/docker-deploy.md">Docker deploy guide</a>.</p>
+  <div class="cta-row">
+    <a class="btn" href="/migrate-build-cache-node/">Gradle and Maven setup</a>
+    <a class="btn btn-secondary" href="/">FosterStack home</a>
+  </div>
+</main>
+<footer>
+  <div>
+    <p>FosterStack is not affiliated with, endorsed by, or sponsored by Gradle Inc.
+    "Gradle" and "Develocity" are trademarks of Gradle Inc., used here only to identify
+    compatibility. FosterStack contains no Gradle Inc. code; it is a clean-room implementation
+    of the documented remote build cache HTTP protocol. Apache Maven is a trademark of the
+    Apache Software Foundation; the Maven Build Cache Extension is Apache's project, not
+    ours.</p>
+    <p style="margin-top:.6rem">© 2026 FosterStack · <a href="/regulated/">For regulated markets</a> · <a href="https://github.com/fosterstack/cache">github.com/fosterstack/cache</a> · <a href="mailto:hello@fosterstack.com">hello@fosterstack.com</a></p>
+  </div>
+</footer>
+</body>
+</html>
diff --git a/sitemap.xml b/sitemap.xml
index 8c1e470..9ecdf10 100644
--- a/sitemap.xml
+++ b/sitemap.xml
@@ -16,4 +16,8 @@
     <changefreq>weekly</changefreq>
     <priority>1.0</priority>
   </url>
+  <url>
+    <loc>https://fosterstack.com/build-cache-server-sizing/</loc>
+    <lastmod>2026-10-08</lastmod>
+  </url>
 </urlset>