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c-treeACE V11.0 Update Guide

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Linux Direct I/O (UNBUFFERED I/O) Performance Support

In V11 and later, support for direct I/O has been enabled on Linux systems. A value of 512-bytes is used for size and alignment for direct I/O.

This feature supports both c-tree data and index files, as well as transaction logs. Configuration options are provided for both.

  • UNBUFFERED_IO filename (enables direct I/O for the specified file; the filename can include wildcards, such as *.dat)
  • UNBUFFERED_LOG_IO YES (enables direct I/O for the transaction logs).

Note: This feature requires Linux kernel version 2.6 or later, c-treeACE Server logs an error message to CTSTATUS.FCS if these options are used on pre-2.6 Linux kernel systems. The error messages are:

The UNBUFFERED_IO option requires Linux kernel version 2.6 or later

The UNBUFFERED_LOG_IO option requires Linux kernel version 2.6 or later

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