SAS System Options under Windows

SGIO System Option: Windows

Activates the Scatter/Gather I/O feature.

Default:	NOSGIO
Valid in:	configuration file, SAS invocation
Category:	Files: SAS Files
PROC OPTIONS GROUP=	SASFILES
Windows specifics:	all

Syntax
Details
See Also

Syntax

-SGIO | -NOSGIO

SGIO: specifies to activate the scatter-read / gather-write feature. The scatter-read / gather-write feature remains active until your SAS session ends.
NOSGIO: specifies not to activate the scatter-read/gather-write feature.

Details

The SGIO system option greatly improves I/O performance for SAS I/O files (data sets, catalogs, indexes, utility files, and other I/O files) when the PC has a large amount of RAM. Scatter-read / gather-write bypasses intermediate buffer transfers between memory and disk.

When SGIO is active, SAS uses the number of buffers that are specified by the BUFNO system option to transfer data between disk and RAM. I/O performance usually improves as the value for the BUFNO increases. Try different values of the BUFNO system option to tune each SAS job or DATA step.

The scatter-read / gather-write feature is active only for SAS I/O files that

contain a 4K-multiple pagesize (for example, 4096 or 8192) on 32-bit systems
contain a 8K-multiple pagesize (for example, 8192 or 16384) on 64-bit systems
were not created by using Version 6 of SAS
are accessed sequentially.

If an I/O file does not meet these criteria, SGIO is inactive for that file even though the SGIO option is specified.