Resources Used by Batch Workloads

Batch workloads are a hybrid between online transaction processing (OLTP) and decision support system (DSS) workloads, and their effect on the system lies somewhere between the two. A batch workload can consist of many repetitive transactions to a database, with some heavy computational work for each. A simple example would be the calculation of total sales for the day. In this case, the batch process would retrieve every sales transaction for the day from the database, extract the sales amount, and maintain a running sum.

Batch processing typically places high demands on both processor and I/O resources, since a large amount of CPU is required for the batch process and the database, and a large number of I/Os are generated from the backend database for each transaction retrieved.

A batch workload is controlled by effectively limiting the rate of consumption of both CPU and I/O. Solaris Resource Manager allows fine-grained resource control of CPU, but I/O resources must be managed by allocating different I/O devices to each workload.

Two methods are typically used to isolate batch resource impact:

• Make a copy of the database on a separate system and run the batch and reporting workloads on that separate system. (Note, however, that in most situations, the batch process updates parts of the online database and cannot be separated from it.)

• Use CPU resource control.

Because the amount of I/O generated from a batch workload is proportional to the amount of CPU consumed, limits on CPU cycles can be used to indirectly control the I/O rate of the batch workload. Note, however, that care must be taken to ensure that excessive I/O is not generated on workloads that have very light CPU requirements.