Effective capacity is a representation of how much data can be written to the system by hosts and applications. The system can store more application data than the physical capacity configured due to benefits of data reduction. The amount of effective capacity depends on the amount of memory configured in the system nodes. The amount of memory configured is based on a default data reduction savings value of 5:1 (3:1 for CKD emulation).

For example, a system configured with 100TB of physical capacity will present 500TB of effective capacity. This is the maximum amount of effective capacity available. The maximum amount of available effective capacity can change as data is written to the system. Maximum values of effective capacity are determined when the system is sized and will vary based on sizing options. The sizing process provides the option to select the most recent release and an N-1 release. The default savings when selecting the most recent release is 5:1. Selecting the N-1 option will set the default savings to 4:1. In addition, the savings value can be manually adjusted within the range 1:1 – 10:1.