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AdministeringIn addition to administering the database server, you can tune performance, replicate data, and archive data.
System administrationThese topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning HCL Informix® database servers.
Performance GuideThe Informix® Performance Guide describes how to configure and operate your HCL Informix® database server to improve overall system throughput and to improve the performance of SQL queries.
Effect of configuration on memory utilizationThe combination of operating-system and Informix® configuration parameters can affect memory utilization.
Shared memoryYou must configure adequate shared-memory resources for the database server in your operating system. Insufficient shared memory can adversely affect performance.
Estimating the size of the resident portion of shared memoryYou can use formulas to estimate the size of the resident portion (in KB) of shared memory when you allocate operating-system shared memory.

Estimating the size of the resident portion of shared memory

You can use formulas to estimate the size of the resident portion (in KB) of shared memory when you allocate operating-system shared memory.

About this task

The result of your calculations is an estimate that normally, slightly exceeds the actual memory that is used for the resident portion of shared memory.

The following estimate was calculated to determine the resident portion of shared memory on a 64-bit server. The sizes that are shown are subject to change, and the calculation is approximate.

Procedure

To estimate the size of the resident portion of shared memory

Calculate the values in the following formulas:

locks_value = LOCKS * 136
logbuff_value = LOGBUFF * 1024 * 3
physbuff_value = PHYSBUFF * 1024 * 2

Calculate the estimated size of the resident portion in KB, using the following formula:

rsegsize = 1.02 * (locks_value + logbuff_value 
           + physbuff_value + 1,200,000) / 1024

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