Dynamic Provisioning concepts
Dynamic Provisioning is a volume management feature that allows storage managers and system administrators to efficiently plan and allocate storage to users or applications. It provides a platform for the array to dynamically manage data and physical capacity without frequent manual involvement.
Dynamic Provisioning provides three important capabilities: as-needed provisioning of storage, enhanced volume performance, and larger volume sizes.
Dynamic Provisioning is more efficient than traditional provisioning strategies. It is implemented by creating one or more Dynamic Provisioning pools (DP pools) of physical storage space using multiple LDEVs. Then, you can establish virtual DP volumes (DP-VOLs) and associate them to 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 42-MB pool page units) is automatically assigned to a DP-VOL from the associated DP pool as that 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 that volume's assigned pages are returned to the pool's free page list. This handling of logical and physical capacity is called thin provisioning. In many cases, logical capacity will exceed physical capacity.
Dynamic Provisioning also enhances volume performance. This is an automatic result of how DP-VOLs map capacity from individual DP pools. A pool is created using from one to 1024 LDEVs (pool volumes) of physical space. Each pool volume is sectioned into 42-MB pages. Each page is consecutively laid down on a number of RAID stripes from one pool volume. The pool's 42-MB pool pages are assigned on demand to any of the DP-VOLs that are connected to that pool. Other pages assigned over time to that DP-VOL randomly originate from the next free page of some other pool volume in the pool.
Setting up a Dynamic Provisioning environment requires a few extra steps. Similar to basic provisioning, you still configure various array groups to a desired RAID level and create one or more volumes (LDEVs) on each of them (see Creating an LDEV). Then set up a Dynamic Provisioning 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 Dynamic Provisioning virtual volumes (DP-VOLs), where 42-MB pages of data are randomly assigned on demand.