You must update the VM directory entry of each database machine that is to use accounting before you can use the accounting facility. For example, suppose the VM directory entry for a database machine contains:
OPTION MAXCONN 32
Update the statement as follows:
OPTION MAXCONN 32 ACCT
Use your normal procedures for updating the VM directory. When you add the ACCT operand, the database machine is correctly defined to use the accounting facility.
Another factor you need to consider is how the number of records that are generated will affect your current VM system accounting file. Your current procedures for handling spool-file-full conditions should handle the additional accounting records. However, you may want to increase the value of the LIMIT operand of the CP SYSACNT macro (if you use that operand). You could also allocate more DASD spool space, or close the file more often. Initially, you should use your current procedures until you get an idea of how many accounting records are generated by the DB2 Server for VM activity at your installation.
To make a general initial estimate of how many accounting records can be generated, start the application server for normal multiple user mode access, and at the end of the day, issue the DB2 Server for VM operator commands COUNTER BEGINLUW and COUNTER CHKPOINT. The number of accounting records generated at your installation is smaller than, but proportional to, these values. That is, the database manager writes an accounting record for a user on some ends of logical units of work, and on all checkpoints. Three more accounting records are written for each run of the database manager: one for initialization, one for operation, and one for termination. You can ignore these three records when making your estimate.
For example, assume that your counters show that your installation does 2 000 logical units of work and 200 checkpoints a day. On average, these result in 1 000 accounting records generated for users (and 200 records generated for checkpoints). For environments with heavy ISQL usage, the number of records generated for users would probably be lower. Do overestimate the number of accounting records.
If you want to provide account or project numbers on the accounting records, you must code a program, as the database manager does not provide code to query users or applications for these numbers. Instead, it provides an exit to an accounting module you can modify. If you want to supply installation-dependent information, consider using an accounting exit before using the accounting facility. For more information, see Supplying Account Numbers for Users.
When you have updated all the database machines and have made provisions for the VM system accounting file and accounting exits, you can use the accounting facility.