Allocating storage to a thin provisioning logical volume

A storage system comprising:

• a first storage system coupled to a computer;
• and
• a second storage system coupled to the first storage system;
• wherein the first storage system includes a first controller providing a thin provisioning logical volume (LU) to the computer;
• wherein the second storage system includes a plurality of second storage devices, and a second controller providing an external thin provisioning LU to the first storage system;
• wherein the first controller is configured to:
• provide pool areas, which are associated with the thin provisioning LU, including a first pool area mapped to a second region in the external thin provisioning LU, and, allocate the first pool area to a first region in the thin provisioning LU to store a write data to the first region in the thin provisioning LU from the computer;
• and
• wherein the second controller is configured to allocate at least one of a plurality of external pool areas, which are provided by at least one of the second storage devices, to the second region in the external thin provisioning LU to store the write data to the first region in the thin provisioning LU.

A method implemented in a storage system having a first storage system coupled to a computer, the first storage system including a plurality of first storage devices;

• and
• a second storage system coupled to the first storage system, the second storage system including a plurality of second storage devices, the method comprising:
• providing, by the first storage system, a plurality of thin provisioning logical volumes (LUs) to the computer;
• providing, by the second storage system, a plurality of external LUs to the first storage system;
• providing, by the first storage system, first pool areas which are associated with the thin provisioning LUs;
• detecting, by the first storage system, a shortage of first pool areas that the first pool areas which is not allocated to the thin provisioning LUs are less than a predetermined value;
• sending, by the first storage system, an allocation request to the second storage system;
• receiving, by the first storage system, a response from the second storage system that storage areas in the external LU are mapped to the first storage system;
• and
• allocating, by the first storage system, the first pool area mapped to the storage areas in the external LU to the thin provisioning LU to store a write data to the thin provisioning LU.

A storage system comprising:

• a first storage system coupled to a computer;
• and
• a second storage system coupled to the first storage system;
• wherein the first storage system includes a plurality of first storage devices and a first controller providing a plurality of thin provisioning logical volumes (LUs) to the computer;
• wherein the second storage system includes a plurality of second storage devices and a second controller providing an external LU to the first storage system;
• wherein the first controller is configured to:
• provide first pool areas which are associated with the thin provisioning LUs;
• detect a shortage of first pool areas such that a number of first pool areas which are not allocated to the thin provisioning LUs is less than a predetermined value;
• send an allocation request to the second storage system;
• receive a response from the second storage system that storage areas in the external LU are allocated to the first storage system;
• and
• allocate the first pool area mapped to the external LU to the thin provisioning LU to store a write data to the thin provisioning LU.