BUFFERS

onconfig.std value

UNIX: 5000
Windows: 2000

units

Number of buffers

range of values

For 32-bit platform on UNIX:
with page size equal to 2048 bytes:
100 through 1,843,200 buffers
(1843200 = 1800 * 1024)

with page size equal to 4096 bytes:
100 through 921,600 buffers
(921,600 = ((1800 * 1024)/4096) * 2048 )

For 32-bit platform on Windows:
100 through 524,288 buffers (524,288 = 512 * 1024)

For 64-bit platforms: 100 through 2³¹-1 buffers
(For the actual value for your 64-bit platform, see your machine notes. The maximum number of buffers on Solaris is 536,870,912.)

takes effect

When the database server is shut down and restarted

utilities

onstat -b or -B (See onstat -b.)

refer to

The following material:

• Shared-memory buffer pool in the shared-memory chapter of the IBM Informix Administrator's Guide
• RA_PAGES
• RA_THRESHOLD
• Your IBM Informix Performance Guide

BUFFERS specifies the maximum number of shared-memory buffers that the database server user threads have available for disk I/O on behalf of client applications. Therefore, the number of buffers that the database server requires depends on the applications. For example, if the database server accesses 15 percent of the application data 90 percent of the time, you need to allocate enough buffers to hold that 15 percent. Increasing the number of buffers can improve system performance.

In general, buffer space should range from 20 to 25 percent of physical memory. It is recommended that you calculate all other shared-memory parameters after you set buffer space (BUFFERS *system_page_size) to 20 percent of physical memory.