In NEO the object identifier (OID) is used to compute the partition to which the object belongs. An object is always assigned to one and only one partition and cannot be moved to another, but a partition can be replicated multiple times among multiple nodes.
A partition is composed of a number of cells that are just a storage node with a known state. The cell state indicates if the node can be used for load and/or store operations, for example:
UP TO DATE: The node has a full copy of the partition content and can be used for load and store operations, this is the stable state.
OUT OF DATE: The node may have some missing data (or even nothing), it must not be used for loading objects but new objects must be written to. Any cell in this state means that the storage node is replicating missing data and will switch to the state above once it is finished.