Microsoft KB Archive/831908

= Performance is slow if you use Client for NFS and UDP =

Article ID: 831908

Article Last Modified on 8/4/2005

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APPLIES TO


 * Microsoft Windows Services for UNIX 3.0 Standard Edition
 * Microsoft Windows Services for UNIX 3.5

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SYMPTOMS
When you transfer data from any Windows Services for UNIX-based NFS server to a Microsoft Windows-based computer by using the Client for NFS component, and if you use the user datagram protocol (UDP), performance is affected during the transfer of data.



CAUSE
This slow performance occurs because UDP is a connectionless protocol. UDP does not verify whether the data has correctly arrived at the destination.

The application that uses UDP is expected to handle the connection establishment, the acknowledgement, and the retransmission of data (if necessary).



RESOLUTION
To work around this problem, use Transmission Control Protocol (TCP) as the protocol in Client for NFS.



STATUS
This behavior is by design.



MORE INFORMATION
When you use UDP as the protocol for the NFS service, the transfer of data is unreliable.

If you use Transmission Control Protocol (TCP, a connection-oriented protocol), the reliability increases. Reliability is better because TCP establishes a connection between the source and the destination before TCP starts the data transfer.

Additionally, TCP verifies that the destination has received the data. If the destination has not received the data, TCP resends the data. This behavior means that TCP is more reliable during a data transfer.

In Services for UNIX 3.0 and in Services for UNIX 3.5, you can select either TCP or UDP as the NFS protocol on both the server for NFS and the client for NFS:
 * NFS client: Open the Client for NFS window in the Services for UNIX administration console, click the Performance tab, and then select TCP in the Transport protocol list.
 * NFS server: Open the Server for NFS window in the Services for UNIX administration console, click the Server Settings tab, and select the Enable TCP support check box.

Keywords: kbprb KB831908

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