Progress
Database Administration
Guide and Reference


Direct I/O (-directio)

Operating 
System 
and Syntax 
UNIX 
Windows 
-directio 
Use 
With 
Maximum 
Value 
Minimum 
Value 
Single-user 
Default 
Multi-user 
Default 
CC, DBS
Not enabled
Not enabled

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. 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 a Progress database.

You might improve 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 the database.

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


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