Patent ID: 7263578
Filing Date: 2007-08-28
Classification: G06F

Abstract:
1. A method for managing disk space in a first storage system, said first storage system being coupled with an external storage system, the external storage system presenting at least one external storage volume configured with a plurality of physical storages in the external storage system as a storage resource to the first storage system, the first storage system presenting at least one virtual volume as a storage resource to a host device, the method for managing disk space in the first storage system comprising: managing a plurality of segments, including a first segment and a second segment from at least one first storage volume configured with a plurality of physical storages in the first storage system as free segments in a free segment pool; mapping the first and second segments from the free segment pool to the at least one virtual volume so as to present the first and second segments via the virtual volume to the host device; determining whether a number of the free segments in the free segment pool is below a predetermined threshold; adding another segment from the at least one first storage volume of the first storage system to the free segment pool when the number of the free segments in the free segment pool is below the predetermined threshold; and adding at least one segment to the free segment pool from the at least one external storage volume of the external storage system when the number of the free segments in the free segment pool is still below the predetermined threshold after adding the another segment from the at least one first storage volume of the first storage system.