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1-34 IBM Informix OnLine Database Server Administrator’s Guide
Shared-Memory Parameter Guidelines
BUFFERS
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
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.