US Patent 8108640 Reserving a thin provisioned space in a storage system

A storage system includes a storage space provisioning system coupled to a primary storage server and a secondary storage server to resize a thin provisioned secondary volume on the secondary storage server. The storage space provisioning system detects data stored on a primary volume that is to be transferred to a secondary volume and obtains a point-in-time copy of the data stored on the primary volume. The storage provisioner determines a maximum transfer size of the data to be transferred using the point-in-time copy, and compares the maximum transfer size to a difference between the thin provisioned size of the secondary volume and a used size of the secondary volume. The storage space provisioning system increases the thin provisioned size of the secondary volume to be greater than the used size of the secondary volume plus the maximum transfer size when the maximum transfer size is greater than the difference.