Oversubscription considerations

Oversubscription must be done with care. The conservative way to ensure that your application performs as intended is to not oversubscribe at all. Many administrators follow this approach. However, others consider this approach to be too conservative. Some administrators are comfortable with over committing CPU and storage resources, but not with overcommitting RAM. This is because the real-world consequences of over committing RAM are much worse and more unpredictable than overcommitting CPU.

How much oversubscription should be used depends on workload. An approach that works for one customer and one workload may perform poorly for another. Furthermore, the age of the processor is also a factor. Newer processors can support higher levels of CPU oversubscription than older processors. Therefore, it is not possible to provide general guidelines that work safely for all customers, all workloads, and all processor types.

Note: If you are going to oversubscribe resources, we recommend that you oversubscribe storage and CPU resources before you oversubscribe memory resources.