IBM SAN Volume Controller allocates provisioning_group_id , which is an identifier for the provisioning group that is affiliated with the MDisk. A provisioning group is an object that represents a set of managed disks that share physical resources. This is represented differently depending on the back-end storage, as shown in the following examples: 

– A9000: The entire subsystem forms one provisioning group. 

– Storwize V7000: The storage pool forms a provisioning group, which allows more than one independent provisioning group in a system. 

– RAID with compressing drives: An array is a provisioning group that presents physical storage in use much as an external array. 

The parameters physical_capacity  and physical_free_capacity  belong to the MDisk’s provisioning group and indicate the total physical storage capacity and formatted available physical space in the provisioning group that contains this MDisk. 

Note:  It is not recommended to create multiple storage pools out of a MDisks in a single provisioning group. 

