snapraid/beta/design.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="A backup program for disk arrays. It stores parity information of your data and it recovers from up to six disk failures">
    <meta name="keywords" content="snapraid snapshot raid backup disk array redundancy parity">    
    <title>SnapRAID Design</title>
    <link rel="stylesheet" href="style.css">
    <link rel="apple-touch-icon" sizes="180x180" href="/beta/apple-touch-icon.png">
    <link rel="icon" type="image/png" sizes="32x32" href="/beta/favicon-32x32.png">
    <link rel="icon" type="image/png" sizes="16x16" href="/beta/favicon-16x16.png">
    <link rel="manifest" href="/beta/site.webmanifest">
    <script src="script.js"></script>

<!-- Google Analytics 4 -->
<!-- Google tag (gtag.js) -->
<script async src="https://www.googletagmanager.com/gtag/js?id=G-W1Z5FKHYQ4"></script>
<script>
  window.dataLayer = window.dataLayer || [];
  function gtag(){dataLayer.push(arguments);}
  gtag('js', new Date());

  gtag('config', 'G-W1Z5FKHYQ4');
</script>

<!-- Google Universal Analytics -->
<script type="text/javascript">

  var _gaq = _gaq || [];
  _gaq.push(['_setAccount', 'UA-21967501-1']);
  _gaq.push(['_trackPageview']);

  (function() {
    var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
    ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
    var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
  })();
</script>

</head>
<body>
    <header>
        <div class="container nav-container">
            <a href="index" class="logo">
                <img src="android-chrome-192x192.png" width="32" height="32"/>
                SnapRAID
            </a>
            <nav>
                <input type="checkbox" id="menu-toggle">
                <label for="menu-toggle" class="menu-icon"><svg viewBox="0 0 24 24" width="24" height="24" fill="currentColor"><path d="M3 18h18v-2H3v2zm0-5h18v-2H3v2zm0-7v2h18V6H3z"/></svg></label>
                <ul>
                    <li><a href="index" >Home</a></li>
                    <li><a href="ui" >UI & Daemon</a></li>
                    <li><a href="howitworks" >How it Works</a></li>
                    <li><a href="design" class="active">Design</a></li>
                    <li><a href="compare" >Compare</a></li>
                    <li><a href="manual" >Manual</a></li>
                    <li><a href="faq" >FAQ</a></li>
                    <li><a href="support" >Support</a></li>
                    <li><a href="download" class="nav-cta">Download</a></li>
                </ul>
            </nav>
        </div>
    </header>


    <div class="container" style="padding: 4rem 20px;">
        <div style="text-align: center; margin-bottom: 4rem;">
            <h1 style="margin-bottom: 1rem;">Design Philosophy</h1>
            <blockquote style="font-size: 1.5rem; color: var(--text-accent); font-style: italic; margin: 0; padding: 0; border: none; font-family: serif;">
                Simplicity is prerequisite for reliability
            </blockquote>
            <cite style="display: block; margin-top: 1rem; font-size: 1rem; color: var(--text-secondary); font-style: normal;">
                <a href="http://en.wikipedia.org/wiki/Edsger_W._Dijkstra" style="color: var(--text-secondary); text-decoration: underline;">Edsger W. Dijkstra</a>
            </cite>
        </div>

        <!-- Unix Philosophy & Reliability -->
        <div style="max-width: 800px; margin: 0 auto 4rem auto;">
            <p style="font-size: 1.1rem; color: var(--text-secondary); margin-bottom: 1.5rem;">
                <strong style="color: var(--text-primary);">SnapRAID</strong> was created following the <a href="http://en.wikipedia.org/wiki/Unix_philosophy">Unix philosophy</a>:
                <em>Write programs that do one thing and do it well</em>.
            </p>
        </div>

        <div class="grid grid-3-cols" style="margin-bottom: 4rem;">
            <!-- Testing/Verification Card -->
            <div class="card">
                <h3>Reliability</h3>
            <p>
                The first design principle was <strong style="color: var(--text-primary);">reliability</strong>.
                The result is a simple architecture and an easy to understand implementation.
            </p>
                <p>
                    Extensive and automated tests with the runtime checker <a href="http://valgrind.org/">Valgrind</a>
                    and with the <a href="https://github.com/google/sanitizers">Google Sanitizers</a>
                    are done to ensure the correctness of the final application.
                    The test has a <a href="cov/">code coverage of over 90%</a>, measured with <a href="http://ltp.sourceforge.net/coverage/lcov.php">lcov</a>.
                </p>
                <p>
                    SnapRAID is also verified with the
                    <a href="https://scan.coverity.com/projects/snapraid">Coverity Scan</a>
                    and <a href="http://clang-analyzer.llvm.org/">clang</a> static analyzers,
                    and with the <a href="http://lcamtuf.coredump.cx/afl/">American Fuzzy Lop</a> fuzzy tester.
                </p>
            </div>

            <!-- Robustness Card -->
            <div class="card">
                <h3>Robustness</h3>
                <p>
                    The second design principle was <strong style="color: var(--text-primary);">robustness</strong>.
                    It supports any kind of problem. Even on kernel panics, power-downs
                    or any other hard failure at runtime, your redundancy data is in safe hands.
                </p>
                <p>
                    It uses all the possible storage techniques to ensure to always keep consistent
                    redundancy even after critical interruptions.
                </p>
            </div>

            <!-- Efficiency Card -->
            <div class="card">
                <h3>Efficiency</h3>
                <p>
                    The third design principle was <strong style="color: var(--text-primary);">efficiency</strong>.
                    It's a native C application highly optimized to ensure maximum throughput of your disk array.
                </p>
                <p>
                    Integrity checks use the highly efficient <a href="http://code.google.com/p/smhasher/">murmur3</a>
                    and <a href="http://burtleburtle.net/bob/hash/spooky.html">SpookyHash</a> hashes at 128 bits.
                </p>
                <p>
                    Redundancy computations use a custom <a href="https://github.com/amadvance/snapraid/tree/master/raid">RAID library</a>
                    (based on Linux Kernel RAID) supporting up to six parity levels.
                    Internal structures use <a href="http://www.tommyds.it/">TommyDS</a>.
                </p>
            </div>
        </div>
    </div>

    <!-- Footer -->
    <footer>
        <div class="container footer-content">
            <div class="footer-col">
                <h3>SnapRAID</h3>
                <p>Copyright &copy; 2026 Andrea Mazzoleni</p>
                <p class="license">Distributed under GPL v3 License</p>
            </div>
            <div class="footer-col">
                <h4>Community</h4>
                <ul>
                    <li><a href="https://www.reddit.com/r/Snapraid/">Reddit r/snapraid</a></li>
                    <li><a href="https://sourceforge.net/p/snapraid/discussion/1677233/">SourceForge Forum</a></li>
                    <li><a href="https://github.com/amadvance/snapraid/">GitHub</a></li>
                </ul>
            </div>
        </div>
    </footer>
</body>
</html>