Configuration Parameters That Affect Data Replication and Auditing

Data replication and auditing are optional. To obtain immediate performance improvements, you can disable these features, provided that the operating requirements for your system allow you to do so.

Data Replication

Data replication typically adds overhead to logical-log I/O that is proportional to your logging activity. A configuration that optimizes logging activity without data replication is likely to optimize logging with data replication.

The following configuration parameters affect data-replication performance:

• DRINTERVAL
• DRTIMEOUT

The DRINTERVAL configuration parameter indicates whether the data-replication buffer is flushed synchronously or asynchronously to the secondary database server. If this parameter is set to flush asynchronously, it specifies the interval between flushes. Each flush impacts the CPU and sends data across the network to the secondary database server.

The DRTIMEOUT configuration parameter specifies the interval for which either database server waits for a transfer acknowledgment from the other. If the primary database server does not receive the expected acknowledgment, it adds the transaction information to the file named in the DRLOSTFOUND configuration parameter. If the secondary database server receives no acknowledgment, it changes the data-replication mode as the DRAUTO configuration parameter specifies. For more information on data replication, see your IBM Informix: Dynamic Server Administrator's Guide.

Auditing

The effect of auditing on performance is largely determined by the auditing events that you choose to record. Depending on which users and events are audited, the impact of this feature can vary widely. Infrequent events, such as requests to connect to a database, have low performance impact. Frequent events, such as requests to read any row, can generate a large amount of auditing activity. The more users for whom such frequent events are audited, the greater the impact on performance. For information about auditing, see the IBM Informix: Trusted Facility Guide.

The following configuration parameters affect auditing performance:

• ADTERR
• ADTMODE

The ADTERR configuration parameter specifies whether the database server is to halt processing for a user session for which an audit record encounters an error. When ADTERR is set to halt such a session, the response time for that session appears to degrade until one of the successive attempts to write the audit record succeeds.

The ADTMODE configuration parameter enables or disables auditing according to the audit records that you specify with the onaudit utility. Records are written to files in the directory that the AUDITPATH parameter specifies. The AUDITSIZE parameter specifies the size of each audit-record file.