1. Test Network Configuration

1. Test Network Configuration

You require the database server to be tested known as the system under test (SUT) installed and configured with the target database server. You also require a load generation server to run HammerDB installed with the HammerDB software and a database client. Typically the load generation server is run on a separate system from the SUT with the load generated across the network. It is possible to run HammerDB on the same system as the SUT however this will be expected to produce different results from a network based load. Both the SUT and the load generation server may be virtualized or container databases although similarly results may differ from a native hardware based installation.

1.1. SUT Database Server Configuration

The database server architecture to be tested must meet the minimum requirements for your chosen database software, however to reach maximum performance it is likely that the specifications will considerably exceed these standard. To run a HammerDB transactional load test there are minimum requirements in memory and I/O (disk performance) to prevent these components being a bottleneck on performance. For a configuration requiring the minimal level of memory and I/O to maximize CPU utilization keying and thinking time should be set to FALSE (keying and thinking time is detailed later in this guide). To achieve this you should aim to create a schema with approximately 250-500 warehouses per CPU socket. As long as it is not too small resulting in contention the schema size should not significantly impact results. You should have sufficient memory to cache as much of your test schema in memory as possible. If keying and thinking time is set to TRUE you will need a significantly larger schema and number of virtual users to create a meaningful system load. Reductions in memory will place more emphasis on the I/O performance of the database containing the schema. If the allocated memory is sufficient most of the data will be cached during an OLTP test and I/O to the data area will be minimal. As a consequence the key I/O dependency will be to the redo/WAL/transaction logs for both bandwidth and sequential write latency. Modern PCIe SSDs when correctly configured have been shown to provide the capabilities to sustain high performance transaction logging.

1.2. Load Generation Server Configuration

The most important component of the load generation server is the server processor. The overall load generation server capacity required depends on the system capabilities of the SUT. It is recommend to use an up to date multi-core processor. HammerDB is a multi-threaded application and implicitly benefits from a multi-core server CPU. To determine whether CPU capacity is sufficient for testing you can monitor the CPU utilisation with HammerDB Metrics. CPU utilisation reaching 100% is an indication that the CPU on the load generation server is limiting performance. Load generation memory requirements are dependent on the operating system configuration and the number of virtual users created with each virtual user requiring its own database client. Typically server sizing guidelines should be within the limits expected to support a real user count. Multiple load generation servers connected in a “master-slave” configuration are enabled within HammerDB to exceed the capacity of a single load generation client. The load generation server does not need to be running the same version of SQL Server as the SUT.

1.3. Administrator PC Configuration

When using the graphical version of HammerDB the administrator PC must have the minimal requirement to display the graphical output from the load generation server. The PC should also have the ability to connect to the SUT to monitor performance by the installation of an appropriate database client.