PHYSBUFF

onconfig.std
value

32

units

Kilobytes

range of values

Page size through PHYSFILE

takes effect

When shared memory is initialized

refer to

Physical-log buffer in the shared-memory chapter of the IBM Informix: Administrator's Guide

PHYSBUFF specifies the size in kilobytes of each of the two physical-log buffers in shared memory. Double buffering permits user threads to write to the active physical-log buffer while the other buffer is being flushed to the physical log on disk. The value of the PHYSBUFF parameter determines how frequently the database server needs to flush the physical-log buffer to the physical-log file.

A write to the physical-log buffer is exactly one page in length. Choose a value for PHYSBUFF that is evenly divisible by the page size. If the value of PHYSBUFF is not evenly divisible by the page size, the database server rounds down the size to the nearest value that is evenly divisible by the page size.

The minimum value for PHYSBUFF is the size of one page. The recommended value for PHYSBUFF is 16 pages.