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<ul>
<li><strong>what</strong>:使用LRU的一个巨大的hashtable。定时遗忘，high throughput</li>
<li><strong>why</strong>：集合很多web server 的内存, use memory is fast and low latency</li>
<li><strong>how</strong>: 出问题回disk找</li>
<li><strong>problem</strong>：没有稳定的存储</li>
<li>handle common problem, much simple</li>
<li>Designed for volatile data
<ul>
<li>failure: just go to disk</li>
<li>recovery: just turn back on and wait. repopulated again</li>
</ul>
</li>
</ul>
<h1 id="redis">redis<a aria-hidden="true" class="anchor-heading icon-link" href="#redis"></a></h1>
<p>REmote DIctionary SErver</p>
<ul>
<li><strong>what</strong>: 支持多种数据类型，LRU，稳定存储</li>
<li><strong>why</strong>: 解决同样的问题</li>
<li><strong>how</strong>：定时写回disk，持久。
<ul>
<li>simple client: ask any node and get redirected.(redirected may take long time)</li>
<li>smart client: know the map, return this to the client(map maybe useless later)</li>
</ul>
</li>
</ul>