Performance during Multi-Threaded Writing / Reading

In this pattern we test the controller’s ability to perform multi-threaded sequential writing/reading. Since it is the first time we are using this type of workload to test controller cards and hard disk drives, it makes sense to tell you a little bit more about the major testing principles and methodology.

So, the task is to emulate simultaneous workload on the storage subsystem imposed by a few applications that have requested “large files”. There will be a special test agent of the IOMeter program that will emulate the above mentioned applications (in Intel IOMeter terms it is called Worker ). This agent will read/write a sequence of 64KB blocks of data starting with some initial segment. Let’s call this process thread .

We are increasing the number of outgoing requests from the Worker (from 1 to 8 with the increment equal to 1). This allows us to study how well the controller can reorganize requests (i.e. combine several requests for sequential data into a single request).

By increasing the number of Workers, we make it harder for the storage subsystem, because in real-life situation several simultaneously working programs will compete with one another for the priority access to the hard disk drives. Each Worker processes its own data (i.e. the addresses of the requested data blocks do not coincide by different Workers).

We will consider two cases: when all programs read the data and all programs write the data. Of course, there can be a lot of different workload combinations, but so far we decided to take into consideration the following ones: