傳輸中 Exchange 伺服器的高可用性Transport high availability in Exchange Server

在 Exchange 伺服器上,傳輸高可用性負責的郵件之前和之後會順利傳遞郵件的備援副本。In Exchange Server, transport high availability is responsible for keeping redundant copies of messages before and after the messages are successfully delivered. 這些功能引進的 Exchange 2013 為 Exchange 2010 中的傳輸高可用性功能的改善,(例如,陰影備援和傳輸暫放) 可協助確保郵件不會在傳送的過程中遺失。These features were introduced in Exchange 2013 as improvements to the transport high availability features in Exchange 2010 (for example, shadow redundancy and the transport dumpster) to help ensure messages aren't lost in transit.

改善傳輸高可用性在 Exchange 2013 中,Exchange 2016 和 Exchange 2019 比 Exchange 2010 的主要功能包括:Key features that improve transport high availability in Exchange 2013, Exchange 2016, and Exchange 2019 over Exchange 2010 include:

  • 陰影備援會郵件已接受或認可之前,在另一部伺服器上建立郵件的備援副本。Shadow redundancy creates a redundant copy of the message on another server before the message is accepted or acknowledged. 傳送伺服器的支援或不支援陰影備援沒有關係。The sending server's support or lack of support for shadow redundancy is irrelevant.

  • 陰影備援可以識別資料庫可用性群組 (Dag) 和 Active Directory 站台為傳輸高可用性界限。Shadow redundancy recognizes both database availability groups (DAGs) and Active Directory sites as transport high availability boundaries. 這可減少可保留郵件的備援複本,並且消除不必要的多餘郵件維護流量跨 Dag 或 Active Directory 的伺服器數量的網站。This reduces the number of servers that can hold redundant copies of messages, and eliminates unnecessary redundant message maintenance traffic across DAGs or Active Directory sites.

    如需詳細資訊,請參閱陰影備援的 Exchange 伺服器For more information, see Shadow redundancy in Exchange Server.

  • 傳輸暫放經過改進,現在稱為Safety NetThe transport dumpster has been improved and is now named Safety Net. Safety Net 儲存在信箱伺服器上的傳輸服務成功處理的郵件。Safety Net stores messages that were successfully processed by the Transport service on Mailbox servers. Safety Net 最適合的信箱伺服器在 DAG 中,但 Safety Net 也適用於多個相同的 Active Directory 站台中不屬於 DAG 的信箱伺服器。Safety Net works best for Mailbox servers in a DAG, but Safety Net also works for multiple Mailbox servers in the same Active Directory site that don't belong to a DAG.

  • 另一部伺服器上 Safety Net 本身是現在進行備援。Safety Net itself is now made redundant on another server. 這是很重要避免單一失敗點,因為的傳輸服務以及信箱資料庫都位於信箱伺服器上。This is important to avoid a single point of failure, because the Transport service and the mailbox databases are both located on the Mailbox server.

    如需詳細資訊,請參閱Safety Net 在 Exchange 伺服器For more information, see Safety Net in Exchange Server.

此圖提供傳輸高可用性在 Exchange Server 中的運作方式的高階概觀。This diagram provides a high-level overview of how transport high availability works in Exchange Server.

傳輸高可用性概觀

  1. 名為 mailbox01 之 Exchange Mailbox server 會從傳輸高可用性界限外部 SMTP 伺服器接收郵件。An Exchange Mailbox server named Mailbox01 receives a message from an SMTP server that's outside the transport high availability boundary. 傳輸高可用性界限為 DAG 或 Active Directory 站台非 DAG 環境中。The transport high availability boundary is a DAG or an Active Directory site in non-DAG environments. 郵件可能是來自:The message could come from:

    • 內部第三方訊息伺服器。An internal third-party messaging server.

    • 是經由在信箱伺服器上的 Front End Transport 服務的網際網路郵件的伺服器。An Internet messaging server that's proxied through the Front End Transport service on a Mailbox server.

    • 在您的組織中的另一部 Exchange 伺服器。Another Exchange server in your organization.

  2. 之前在認可收到郵件,Mailbox01 啟動名為 Mailbox03 之位於傳輸高可用性界限,另一部 Exchange 信箱伺服器的新 SMTP 工作階段,而且 Mailbox03 進行郵件的陰影複製。Before acknowledging receipt of the message, Mailbox01 initiates a new SMTP session to another Exchange Mailbox server named Mailbox03 that's within the Transport high availability boundary, and Mailbox03 makes a shadow copy of the message. 在 DAG 環境中,遠端 Active Directory 站台中的陰影伺服器是慣用的。In DAG environments, a shadow server in a remote Active Directory site is preferred. Mailbox01 是持有主要郵件的主要伺服器,且 Mailbox03 是持有陰影郵件的陰影伺服器。Mailbox01 is the primary server holding the primary message, and Mailbox03 is the shadow server holding the shadow message.

  3. Mailbox01 上的傳輸服務會處理主要郵件。The Transport service on Mailbox01 processes the primary message.

    a.a. 在這個範例中,收件者信箱位於 Mailbox01 上,所以傳輸服務會將郵件傳輸至本機信箱傳輸服務。In this example, the recipient's mailbox is located on Mailbox01, so the Transport service transmits the message to the local Mailbox Transport service.

    b.b. 信箱傳輸服務再將郵件傳遞到本機信箱資料庫。The Mailbox Transport service delivers the message to the local mailbox database.

    c.c. Mailbox01 排入佇列,指出已經成功處理主要郵件,且 Mailbox01 將主要郵件的複本移至本機主要 Safety Net mailbox03 的捨棄狀態。Mailbox01 queues a discard status for Mailbox03 that indicates the primary message was successfully processed, and Mailbox01 moves a copy of the primary message into the local Primary Safety Net. 請注意,郵件會佇列在相同佇列資料庫之間移動。Note that the message moves between queues within the same queue database.

  4. Mailbox03 會定期輪詢 Mailbox01 關於主要郵件的捨棄狀態。Mailbox03 periodically polls Mailbox01 for the discard status of the primary message.

  5. 當 Mailbox03 判斷 Mailbox01 已成功處理主要郵件時,Mailbox03 將會將陰影郵件移至本機陰影 Safety Net。When Mailbox03 determines Mailbox01 successfully processed the primary message, Mailbox03 moves the shadow message into the local Shadow Safety Net. 請注意,郵件會佇列在相同佇列資料庫之間移動。Note that the message moves between queues within the same queue database.

郵件會保留在主要 Safety Net 及陰影 Safety Net 郵件到期之前,根據可設定的逾時值。The message is retained in Primary Safety Net and Shadow Safety Net until the message expires based on a configurable timeout value. 如果信箱資料庫容錯移轉發生郵件過期前,Mailbox01 上主要 Safety Net 重新提交郵件。If a mailbox database failover occurs before the message expires, the Primary Safety Net on Mailbox01 resubmits the message. 如果無法使用 Mailbox01,陰影 Safety Net 在 Mailbox03 會接管並重新提交郵件。If the Mailbox01 isn't available, the Shadow Safety Net on Mailbox03 takes over and resubmits the message.

在信箱伺服器上的前端傳輸服務中的郵件備援Message redundancy in the Front End Transport service on Mailbox servers

在信箱伺服器 (Client Access 服務的一部分) 上的 Front End Transport 服務有無訊息佇列。The Front End Transport service on a Mailbox server (part of the Client Access services) has no message queues. 它是可接受的傳入 SMTP 連線,無狀態 proxy 與 proxy 它們的傳輸服務的信箱伺服器。It's a stateless proxy that accepts incoming SMTP connections, and proxies them to the Transport service on a Mailbox server. Front End Transport 服務保持開啟狀態時,傳送伺服器的 SMTP 工作階段:The Front End Transport service keeps the SMTP session with the sending server open while:

  • 主要的郵件會傳送至 Mailbox server 上的傳輸服務。The primary message is transmitted to the Transport service on a Mailbox server.

    and

  • 傳輸高可用性界限 (DAG 或 Active Directory 站台) 內的不同信箱伺服器上的傳輸服務是建立郵件陰影複製。A shadow copy of the message is made by the Transport service on a different Mailbox server within the transport high availability boundary (DAG or Active Directory site).

僅主要郵件及陰影郵件已成功建立之後,資料 SMTP 命令的結尾會傳送回透過前端傳輸服務傳送郵件的 SMTP 伺服器。Only after both the primary message and shadow message are successfully created, the end of data SMTP command is sent back to the sending SMTP server through the Front End Transport service.