IBM 000-8697 User Manual

IBM Informix OnLine Database Server Administrator’s Guide

BUFFERS

specifies the maximum number of shared-memory buffers available

to OnLine user processes during processing.

The minimum value for

BUFFERS

is 4 per user process. The maximum value

is 32,000. The default value is 200.

As a general guideline, buffer space should range from 20 to 25 percent of
physical memory. Informix recommends that you initially set

BUFFERS

 so

that buffer space (the value of

BUFFERS

 multiplied by

BUFFSIZE

) is equal to

20 percent of physical memory. Then calculate all other shared-memory
parameters.

If you find that after you have configured all other parameters you can afford
to increase the size of shared memory, increase the value of

BUFFERS

 until

buffer space reaches the recommended 25 percent upper limit.

TBLSPACES

 specifies the maximum number of active (open) tblspaces.

Temporary tables and system catalog tables are included in the active table
count.

The minimum value for

TBLSPACES

 is 10 per user process. This minimum

must be greater than the maximum number of tables in any one database,
including the system catalog tables, plus 2. (This minimum is required to
permit OnLine to execute a

DROP DATABASE

 statement.) The maximum

value is 32,000. The default value is 200. Consider the demands of your appli-
cation when you assign a value.