This disclosure enables a user to incrementally increase or decrease the size of the cluster and, in particular, to incrementally increase or decrease the number of map regions implemented in a metadata manager associated with the cluster while maintaining availability of the cluster. In a representative embodiment, a configurable target map size is identified, either manually (e.g., by the user) or programmatically. If the target map size is found to be within an acceptable value (given the available node configuration), a procedure to create a new map is triggered. The new map preferably is generated as follows. Initially, one or more new temporary region(s) are created either to split or join the existing regions (depending on whether the map is being increased or decreased). For each temporary region, the process also generates MDPL backup regions. Metadata from an original region (or regions) is then migrated to the temporary region(s). Once the migrations have been completed, the old region or regions (from which the metadata is migrated) are removed and what were the temporary regions are, in effect, promoted. The result is the new map.