Dynamic Provisioning for Mainframe is a volume management feature that provides a platform for the array to dynamically manage data and physical capacity without frequent manual involvement. Dynamic Provisioning for Mainframe provides three important capabilities: as-needed provisioning of storage, enhanced default volume performance, and larger volume sizes.
To implement dynamic (thin) provisioning, you create one or more Dynamic Provisioning for Mainframe pools (DP pools) of physical storage space using multiple LDEVs. Then, you can establish virtual DP volumes (DP-VOLs) and associate them with the individual DP pools. In this way, capacity to support data can be optimally assigned on demand within the pool.
DP-VOLs are of a user-specified logical size without any corresponding physical space. Actual physical space, allocated in 38-MB pool page units) is automatically assigned to a DP-VOL from the associated DP pool as the volume's logical space is written to over time. A new DP-VOL does not have any pool pages assigned to it. The pages are loaned out from its associated pool to that DP volume until the volume is reformatted or deleted. At that point, all of the volume's assigned pages are returned to the pool's free page list. In many cases, logical capacity will exceed physical capacity.
Dynamic Provisioning for Mainframe also enhances volume performance by default. This is an automatic result of how DP-VOLs map capacity from individual DP pools. A pool is created using multiple LDEVs (pool volumes) of physical space. Each pool volume is sectioned into 38-MB pages. Each page is consecutively laid down on several RAID stripes from one pool volume. The pool's 38-MB pool pages are assigned on demand to any of the DP-VOLs that are associated with that pool. Other pages assigned over time to that DP-VOL originate from the next free page of some other pool volume in the pool. DP-VOLs are defined as 3390-A volumes that can be larger than traditional volumes. This volume type was created to reduce device address requirements.
Setting up a Dynamic Provisioning for Mainframe environment requires a few extra steps. Like thick provisioning, you still configure various array groups to a desired RAID level and create one or more volumes (LDEVs) on each of them. Then you set up a Dynamic Provisioning for Mainframe environment by creating one or more DP pools of physical storage space that are each a collection of some of these LDEVs (DP pool volumes). This pool structure supports creation of 3390-A Dynamic Provisioning for Mainframe virtual volumes (DP-VOLs), where 38-MB pages of data are assigned on demand.