Tandem Capacity Model (TCM) Manual

Figure 28 Batch Applications
Transaction Types
TCM uses three transaction types: batch, online, and query. In TCM, a batch transaction is roughly
equivalent to the common terms batch job and workload. The batch transaction can have multiple
tasks. Batch transactions have the following characteristics:
• Long job duration—Batch transactions can last several hours and can include processing of
several tasks, each of which includes hundreds or thousands of transactions.
• Low priority—Batch transactions have lower priority than online transactions and do not
normally interfere with the response time of online transactions.
• Significant disk activity—Batch transactions can process hundreds or thousands of smaller
transactions. Each of these smaller transactions can have disk activity.
• Little or no terminal interaction—Batch transactions require little or no operator intervention
and can be run during nonpeak periods such as at night or on weekends.
• Closed system—A batch transaction processes a series of smaller transactions (records)
sequentially with no delay between them.
The completion of the processing of one transaction (record) immediately starts the processing of
the next. The following diagram shows a simple batch transaction or workload. Within the workload
is a closed box representing a task. Within that task are 3,000 transactions to be processed in
the batch workload. The moment one of these 3,000 transactions completes, the next one is started.
A given batch workload has only one active transaction in the system at a time.
Transaction Types 97