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SharePlex 8.6.6 - Preinstallation Checklist

Tune Capture on Exadata

The Capture process can be configured to use multiple capture threads for faster performance on an Exadata system. Capture reads directly from the logs on the Exadata ASM disks.

The SP_OCT_ASM_MULTI_OCI parameter controls the number of threads that Capture uses to read the redo logs.

The value set for this parameter must satisfy all of the following:

  • greater than 1.
  • an even divisor of the number of disks in the ASM disk group that stores the redo logs. For example, if there are 16 disks, the values of 2, 4, 8, and 16 are valid.
  • not larger than the number of disks in the ASM disk group that stores the redo logs.

A large number of threads is not required, and performance actually diminishes with too many threads. The more threads, the more memory Capture requires.

Start with a small number of threads and monitor performance, then add threads if needed until you obtain an ideal balance between performance gain and memory usage. For example, if there are 16 disks, you could start with a value of 2.

To configure SharePlex for multi-threaded capture on Exadata

  1. Run sp_ctrl.
  2. Set the SP_OCT_ASM_MULTI_OCI parameter to the number of threads that you want Capture to use.

    sp_ctrl> set param SP_OCT_ASM_MULTI_OCI 3

  3. Restart Capture.

Note: Capture automatically adjusts its buffer size to the value of the AU_SIZE parameter that is set for the disk group where the logs reside. This is the recommended buffer size for best performance and should not be changed. The SP_OCT_ASM_MULTI_OCI_BLOCK_SIZE parameter can override the default behavior if necessary.

 

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