Progress
Startup Command and Parameter
Reference


Direct I/O (-directio)

Operating 
System
and
Syntax 
UNIX
NT 
-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 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.


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