A capability is a feature that is provided by a volume. For example, a volume may exhibit capabilities such as performance and reliability to various degrees. Each type of capability is defined as a set of rules.
You can create volumes having specific capabilities. A capability is a simple name used to indicate what the capability means. Storage is allocated according to your request. For example, you can ask for a volume to be Performant and Reliable. These are capabilities have parameters such as, number of striped columns or number of mirrors.