Conexão ao SQL Server lenta – a partir do Windows Server 2008/Vista

Alterar o parâmetro AUTOTUNINGLEVEL de NORMAL para DISABLED

Referências:

  • KB 935400
    "It takes much longer than expected to download an e-mail message from a POP3 server in Outlook 2007 or in Outlook 2010"
  • KB 947239
    "Description of the Receive Window Auto-Tuning feature for HTTP traffic on Windows Vista-based computers"

    "The Receive Window Auto-Tuning feature lets the operating system continually monitor routing conditions such as bandwidth, network delay, and application delay. Therefore, the operating system can configure connections by scaling the TCP receive window to maximize the network performance. To determine the optimal receive window size, the Receive Window Auto-Tuning feature measures the products that delay bandwidth and the application retrieve rates. Then, the Receive Window Auto-Tuning feature adapts the receive window size of the ongoing transmission to take advantage of any unused bandwidth."

  • "Performance Enhancements in the Next Generation TCP/IP Stack"
    coluna "Cable Guy" (Microsoft), Novembro/2005

Receive Window Auto-Tuning

The TCP receive window size is the amount of data that a TCP receiver allows a TCP sender to send before having to wait for an acknowledgement. After the connection is established, the receive window size is advertised in each TCP segment. Advertising the maximum amount of data that the sender can send is a receiver-side flow control mechanism that prevents the sender from sending data that the receiver cannot store. A sending host can only send at a maximum the amount of data advertised by the receiver before waiting for an acknowledgment and a receive window size update.

 

Alguns roteadores e sistemas operacionais mais antigos não "conversam" muito bem com esta funcionalidade habilitada.

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