Facebook開發新的開源計時設備，僅需一個PCIe插槽即可工作

{"type":"doc","content":[{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"2021年8月11日，Facebook 分享了其Time cards 硬件和軟件設計。"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":" "}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"2021年8月11日，Facebook工程師分享他們已經構建了一個用於網絡同步的時間設備Time cards並開源了整個規範，該設備基於超精確原子鐘和導航衛星的計時技術，將有助於在大規模互聯網上加速服務。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"每一臺數字設備都需要知道現在是什麼時間，有了時間這個維度，設備才能正確提供各種服務並記錄各種類型的日誌。尤其對於 Facebook 這種擁有幾十億用戶規模的社交網絡而言，沒有精確的時間就無法協調數據中心的工作，因此 Facebook 決定打造自己的計時設備。"}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"NTP和Stratum One各有不足"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":" "}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"在Time cards被分享之前，基本上有兩種方法來檢查時間。開發者會使用NTP（Network TimeProtocol，網絡時間協議）作爲時間檢查機制，但是這種公共 NTP 池增加了對互聯網連接的依賴，並可能影響系統的整體安全性和可靠性。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"運行封閉式數據中心的公司會由一個叫Stratum One的硬件設備來充當時間保持者。但它們是由少數幾家公司多年來建造的，所以很難獲得新的功能，並且因爲它們具有專利性質，所以像Facebook這樣的公司無法控制這些盒子。"}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"新的Time cards更準確、更便宜"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":" "}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"Time Cards 本質上是使用與插入圖形卡和其他設備相同的 PCI Express 擴展卡技術安裝到服務器中的電子板。Facebook 把插有 Time Card 並運行其計時軟件的服務器稱爲時間設備。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"Time Card 通過監聽嵌入在 GNSS 導航衛星無線電信號中的計時信息而保持同步。時間卡潛伏在數據中心的深處，但它們連接到屋頂安裝的天線，以接收衛星信號。之後，包括微型原子鐘在內的一套電子元件會處理獲得的數據，以供數據中心服務器使用。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":" "}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"目前，Time Card 的規格、原理圖、材料清單（BoM）和源代碼等都已託管至GitHub倉庫。如果普通開發者不需要 Facebook 那麼高的時間精度水平，可以通過換上更傳統的晶體振盪器使成本降至約 300 美元。"}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"Facebook工程師表示：希望通過開源工作來幫助更多人"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":" "}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"Facebook 表示，打造一款非常精確、價格低廉且不受供應商限制的設備本身就是一項成就。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":" "}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"他們在早期就決定將設計過程開源，以便其他公司和工程師能夠爲設計做出貢獻。此舉顯示了互聯網大部分公司的合作精神。即使像 Facebook、微軟和谷歌這樣的公司之間會有激烈競爭，他們也會爲可以使競爭對手受益的開源項目做出貢獻。這方面，最好的例子是全球範圍內規模最大的開源軟件項目Linux，它是 Android 手機、SpaceX 航天器、超級計算機和無數數據中心服務器操作系統的基礎。可以說開源使全球信息技術領域發生了全局性、持續性的重大變化，在社會基礎設施建設方面也發揮着越來越重要的作用。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":" "}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"參考鏈接："},{"type":"link","attrs":{"href":"https:\/\/engineering.fb.com\/2021\/08\/11\/open-source\/time-appliance\/","title":null,"type":null},"content":[{"type":"text","text":"https:\/\/engineering.fb.com\/2021\/08\/11\/open-source\/time-appliance\/"}],"marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}]}]}]}