Release 10.1A: OpenEdge Deployment:
Startup Command and Parameter Reference

Direct I/O (-directio)

Use Direct I/O (-directio) to open all files in unbuffered mode, which enables Progress to use an I/O technique that bypasses the operating system buffer pool and transfers data directly from a buffer to disk.

Operating system and syntax	UNIX Windows	-directio
Use with	Maximum value	Minimum value	Single-user default	Multi-user default
Client Connection, Database Server	–	–	Not enabled	Not enabled

This technique has several advantages over buffered reads and writes such as avoiding the overhead of maintaining the operating system buffer pool and eliminating competition for operating system buffers between Progress programs and other programs. The operating system buffer-pool algorithms are designed for efficient sequential file access; the Progress buffer-pool algorithms are more efficient for access to an OpenEdge database.

You might improve Progress performance by using the direct I/O feature. To use direct I/O, use Blocks in Database Buffers (-B) to increase the size of the Progress buffer pool, since Progress I/O does not pass through the operating system buffer pool. Also, decrease the size of the operating system buffer pool to compensate for the additional memory allocated to Progress.

Note: Use asynchronous page writers (APWs). They improve database performance by performing overhead operations in the background.