HP 3PAR StoreServ 7400 2-node HP 3PAR SmartStart 1.1.1 User's Guide ( - Page 42

10 CPGs A Common Provisioning Group (CPG) creates a virtual pool of storage space that allows up to 4,095 virtual volumes to share the CPG's resources. When you create virtual volumes (fully provisioned virtual volumes or Thin volumes), the volumes draw storage space from the CPG's storage space pool. • CPGs dynamically allocate storage space to Thin volumes. Therefore, when a Thin volume is running low on user space, the HP 3PAR StoreServ Storage system automatically assigns more storage capacity to the Thin volume (specifically, the storage system maps new regions-from the logical disks in the CPG associated with the Thin volume-to the Thin volume). Because space is allocated dynamically to Thin volumes, the storage system does not contain large pockets of unused but allocated space. • CPGs allocate a fixed amount of storage space to fully provisioned virtual volumes upon creation. Therefore, the storage system could contain large pockets of unused but allocated space. By default, CPGs are configured to automatically grow over time, as required by application writes, when the amount of available space falls below a configured threshold. Monitoring CPG Growth CPGs require careful planning and monitoring to prevent them from becoming so large that they set off the HP 3PAR StoreServ Storage system's built-in safety mechanisms. These safety mechanisms prevent a CPG from consuming all free space on the system, but they only work properly on systems that are planned carefully and monitored closely. To restrict a CPG's growth and maximum size, configure these monitoring aids when you create the CPG: • Growth increment • Growth warning • Growth limit The maximum number of CPGs per system is 2,048. To create and manage CPGs, use the HP 3PAR Management Console. For more information, see the HP 3PAR Management Console Online Help. 42 CPGs