Metaspace
A metaspace is a virtual entity that contains spaces, which are containers that store the data used by applications.
A metaspace is a container for managing system spaces, user spaces, and a group of members that are working together in a cluster. The metaspace is the initial handle to Legacy ActiveSpaces. An application or member first joins a metaspace, and through it, gets access to other objects and functionality.
A metaspace is created when the first process connects to it, and disappears when the last process disconnects from it. The metaspace grows or shrinks automatically as members connect to it and disconnect from it.
Initially, a metaspace contains only system spaces. As users create spaces in the metaspace, the definition of those spaces (along with other administrative data) is stored in system spaces.
Multiple metaspaces may exist at the same time, each one containing a completely independent set of spaces. This means, for example, that changes to a space called clients in a metaspace named Dev have no impact on a space named clients in a metaspace named Prod. Since no single application can connect to two different metaspaces using the same metaspace name, metaspaces should always use different names.