1.1.4 Understanding Performance

System performance is important to users. Users usually start to notice performance when a system takes longer than one second to respond. Oracle Net configuration can be modified to enhance system performance.

This section discusses performance considerations.

• Listener Queue Size
  
• Session Data Unit Size for Data Transfer Optimization
  
• Persistent Buffer Flushing for TCP/IP
  
• Sockets Direct Protocol
  
• Database Availability
  

1.1.4.1 Listener Queue Size

If you anticipate receiving a large number of connection requests for a listening process (such as a listener or Oracle Connection Manager) over TCP/IP, then Oracle Net enables you to configure the listening queue to be higher than the system default.

1.1.4.2 Session Data Unit Size for Data Transfer Optimization

Before sending data across the network, Oracle Net buffers and encapsulates data into the session data unit (SDU). Oracle Net sends the data stored in this buffer when the buffer is full, flushed, or when database server tries to read data. When large amounts of data are being transmitted or when the message size is consistent, adjusting the size of the SDU buffers can improve performance, network utilization, or memory consumption. You can deploy SDU at the client, application web server, and database.

Tuning your application to reduce the number of round trips across the network is the best way to improve your network performance. If this is done, then it is also possible to optimize data transfer by adjusting the size of the SDU.

Considerations for Modifying the Size of the SDU

Modify the SDU size under the following situations:

• The data coming back from the server is fragmented into separate packets.

• You are on a wide area network (WAN) that has long delays.

• The packet size is consistently the same.

• Large amounts of data are returned.

Do not modify the SDU size under the following situations:

• The application can be tuned to avoid the delays listed in the adjacent column.

• You have a high speed network where the effect of the data transmission is negligible.

• Your requests return small amounts of data from the server.

Note:

Starting with Oracle Database 11g, Oracle Net Services optimizes bulk data transfer for certain components, such as Oracle SecureFiles LOBs and Oracle Data Guard redo transport services. The SDU size limit, as specified in the network parameter files, does not apply to these bulk data transfers. Bulk data transfer optimization does not apply when ASO options are enabled or TLS transport is used.

See Also:

"Configuring Session Data Unit "

1.1.4.3 Persistent Buffer Flushing for TCP/IP

Under certain conditions for some applications using TCP/IP, Oracle Net packets may not get flushed immediately to the network. Most often, this behavior occurs when large amounts of data are streamed. The implementation of TCP/IP itself is the reason for the lack of flushing, causing unacceptable delays. To remedy this problem, specify no delays in the buffer flushing process.

See Also:

Oracle Database Net Services Reference for additional information about the TCP.NODELAY parameter

1.1.4.4 Sockets Direct Protocol

Oracle Net Services provides support for InfiniBand high-speed networks. InfiniBand is a high-bandwidth I/O architecture designed to increase communication speed between CPUs, server-side devices, and network subsystems. Oracle Net Services provides support for Sockets Direct Protocol (SDP). SDP is an industry-standard wire protocol intended for use between InfiniBand network peers.

SDP reduces the overhead of TCP/IP by eliminating intermediate replication of data and transferring most of the messaging burden away from the CPU and onto the network hardware. The result is a low-latency, increased bandwidth, high-throughput connection that reduces the amount of CPU cycles dedicated to network processing.

The communication between clients, including Oracle WebLogic Server or any other third-party middle-tier client, and Oracle Database 12c release onwards can take advantage of high-speed interconnect benefits. Oracle WebLogic Server includes Oracle TCP/IP support as part of its installation.

A driver installed on the Oracle WebLogic Server servers transparently converts TCP/IP support to SDP support. The SDP requests are then sent to an InfiniBand switch that processes and forwards the requests from the Oracle WebLogic Server servers to the database server.

See Also:

"Configuring SDP Support for InfiniBand Connections"

1.1.4.5 Database Availability

Availability to the database is crucial for any network. You can configure multiple listeners to handle client connection requests for the same database service. This is beneficial in Oracle Real Application Clusters configurations, where each instance has a listener associated with it. Multiple listener configurations enable you to use the following features.

• Connect-time failover enables clients to request a different listener, usually on a different node, if the first listener fails.

• Client load balancing enables clients to randomize requests to the multiple listeners, usually on different nodes. These features can be used together or separately. Together, they ensure access to the database and distribute the load to not overburden a single listener.