⋯ 912 unchanged lines
<span class="case-status">Zero downtime</span>
</header>
<div class="case-metrics">
<p class="metric" data-field="impact"><span class="metric-label">Business impact</span>Lower infrastructure cost, higher reliability, and a current critical stack with a clear path to later Java and AWS Graviton modernization.</p>
<p class="metric" data-metric="duration"><span class="metric-label">Duration</span>9 months from start through production rollout. Active engineering duration remains to be normalized.</p>
<p class="metric" data-metric="complexity"><span class="metric-label">Complexity</span>High. Zero downtime, broad dependencies, data and traffic cutover, and a rotating 9 to 25 person roster.</p>
<p class="metric" data-field="impact"><span class="metric-label">Business impact</span>Almost $1M in annual infrastructure savings. Production cutover completed with zero downtime and no data corruption, while establishing a more current operating baseline.</p>
<p class="metric" data-metric="duration"><span class="metric-label">Duration</span>9 months, January through October 2021, from active planning through production rollout. California decommissioning continued afterward.</p>
<p class="metric" data-metric="complexity"><span class="metric-label">Complexity</span>High. About 1,000 instances, 120 application services, 60K requests per second, 1 PB of S3 data, 150 TB of Kylin data, and multiple state and traffic strategies.</p>
</div>
<div class="case-facts">
<section><h4>The change</h4><p>AWS California to AWS Virginia, plus Postgres, Mongo, Kafka, Redis, Flink, Hadoop, Spark, Elasticsearch, ScyllaDB, and Java modernization.</p></section>
<section><h4>The change</h4><p>AWS Northern California to Northern Virginia, including state, applications, traffic, release, monitoring, and infrastructure baselines.</p></section>
<section><h4>The constraint</h4><p>Move a B2B customer portfolio without interruption, including a long tail and very large customers.</p></section>
<section><h4>The method</h4><ul><li>Audit dependencies and upgrade target services in waves.</li><li>Establish dual-run and replication paths.</li><li>Move smallest customers first, then largest.</li></ul></section>
<section><h4>The method</h4><ul><li>Map service dependencies, readers, writers, and data entities.</li><li>Establish replicated event and state paths.</li><li>Move traffic by customer cohort, from test domains to top accounts.</li></ul></section>
</div>
<p class="case-ai"><span>AI-assisted?</span>No.</p>
<a class="deep-dive" data-case-deep-dive="aws-virginia" href="https://thing.unravel.tech/unravel/aws-virginia-migration">Read the full AWS migration deep dive →</a>
</article>
</li>
⋯ 103 unchanged lines