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 page size
(for example, 4096 or 8192) on 32–bit systems
-
contain a 8K-multiple page size
(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. You can access more information on SGIO
in the
SGIO Usage document.