PeSIT tuning

PeSIT tips and tricks provides information on how to optimize Transfer CFT performance.

General recommendations to improve performance include:

  • Minimizing the number of I/O operations
  • Reducing duration of protocol wait state
  • Reducing CPU consumption during the transfer
Note In Central Governance see the PeSIT tuning section on the product configuration page, and the Record format section (under file properties) in the flow definition, for supported tuning features and details.

Attributes tuning

When using Transfer CFT with Central Governance you can adjust and tune the PACING and CHKW settings. All other values described here are preset through Central Governance. To view these values perform an extract of your Transfer CFT configuration.

PDU/NDU formatting

Attributes that are used to control the way to build PDU/NDU are:

  • RRUSIZE and SRUSIZE control the maximum size of an NDU (excluding the TCP header)
  • RPACING and SPACING control the PeSIT data transferred between synchronization points
  • RCHKW and SCHKW control the PeSIT acknowledgment window size
  • The CONCAT attribute enables or not PDU concatenation in one NDU
  • The SEGMENT attribute enables or disables File Sub-record Units

PeSIT attributes are negotiated between the initiator and the responder when opening a PeSIT session. This means that a value proposed by the initiator can be negotiated to a lower value by the responder.

When the maximum size of an NDU (negotiated RUSIZE attribute) is lower than the file record length, File Sub-record Units are unavoidable. In this case, even if SEGMENT attribute is set to NO, Transfer CFT performs the record segmentation.

Additional settings

Pacing= 0

No synchronization is sent, which provides better performance, but without the ability to restart a transfer at a synchronization point.

Chkw = 0

No ack synchronization is sent by the server to the requester. However in the case of a transfer error, a restart is possible.

General recommendations

Minimize I/O operations

Network access and file access affect the overall I/O. To minimize the number of network I/O operations:

Reduce the protocol wait state

The PeSIT protocol relies on a checkpoint mechanism to restart a transfer from a position that is different from the beginning of the file. In PeSIT, the data transferred between synch points (PACING) multiplied by acknowledgment window size (CHKW) defines the maximum amount of unacknowledged data a sender can send before it waits for an acknowledgment back from the receiver.

Tip   An efficient way to reduce the duration of the protocol wait state is to enlarge these values.

Reduce CPU consumption

A high CPU consumption can slow network performance. Therefore it is highly recommended that you disable compression if you have high speed network access. Conversely, compression can be useful on a low speed network.

Additionally segmentation may impact the CPU consumption. To reduce consumption you can, when using binary file type (FTYPE=B), set the FLRECL to the RUSIZE minus 6 (-6).

As formatting File Subrecord Units require CPU resource, the option SEGMENT can slow down network performance. It is preferable to disable this option if you have a high speed network access.

See also the Configuring simultaneous transfers section for additional performance recommendations.

Related topics

Transfer acceleration

Related Links