How much memory to configure

Memory is the most important consideration when you are configuring Adaptive Server. Memory is consumed by various configuration parameters, procedure cache and data caches. Setting the values of the various configuration parameters and the caches correctly is critical to good system performance.

The total memory allocated during boot-time is the sum of memory required for all the configuration needs of Adaptive Server. This value can be obtained from the read-only configuration parameter 'total logical memory'. This value is calculated by Adaptive Server. The configuration parameter 'max memory' must be greater than or equal to 'total logical memory'. 'max memory' indicates the amount of memory you will allow for Adaptive Server needs.

During boot-time, by default, Adaptive Server allocates memory based on the value of 'total logical memory'. However, if the configuration parameter 'allocate max shared memory' has been set, then the memory allocated will be based on the value of 'max memory'. The configuration parameter 'allocate max shared memory' will enable a system administrator to allocate, the maximum memory that is allowed to be used by Adaptive Server, during boot-time.

The key points for memory configuration are:

The System Administration Guide provides a thorough discussion of:

What remains after all other memory needs have been met is available for the procedure cache and the data cache. Figure 15-1 shows how memory is divided.

Figure 15-1: How Adaptive Server uses memory