Dell PowerVault ME5 Series Administrator's Guide

Overcommitting volumes

Overcommitting is a virtual storage feature that allows a system administrator to overcommit physical storage resources. This allows the host system to operate as though it has more storage available than is actually allocated to it. When physical resources fill up, the administrator can add physical storage by adding additional disk groups or expanding an ADAPT disk group.

Paging is required to eliminate the lack of flexibility associated with linear mapping. Linear mapping limits the ability to easily expand the physical storage behind the over-provisioned volume. Paged mapping allows physical resources to be disparate and noncontiguous, making it much easier to add storage on the fly.