BUFFERS

onconfig.std
value

1000

onconfig.xps
value

1000

units

Number of buffers

range of values

100 through 786,432 buffers (786,288 = 768 * 1024)

For any 64-bit platform:
100 through 2³¹-1 (Might be less on some 64 -bit platforms due to operating-system limitations)

takes effect

When shared memory is initialized

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.

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.