Patent ID: 9058293
Filing Date: 2015-06-16
Classification: G06F

Abstract:
1. A method, comprising: receiving, by a storage controller, a request to establish a point-in-time copy operation by placing a space efficient source volume in a point-in-time copy relationship with a space efficient target volume, wherein subsequent to being established the point-in-time copy operation is configurable to consistently copy the space efficient source volume to the space efficient target volume at a point in time; and maintaining, in an extent exception table within the storage controller, indications of which extents of the space efficient target volume are in flight, wherein extents are in flight if tracks of the extents are staging or awaiting to be staged into a cache from the space efficient target volume, or destaging or awaiting to be destaged from the cache to the space efficient target volume, and wherein: if an extent is allocated in the space efficient source volume, and the extent is in flight, then the extent is not released from the space efficient target volume; if the extent is unallocated in the space efficient source volume, and the extent is in flight, then the extent is not released from the space efficient target volume; if the extent is allocated in the space efficient source volume, and the extent is not in flight, then the extent is released from the space efficient target volume; and if the extent is unallocated in the space efficient source volume, and the extent is not in flight, then the extent is released from the space efficient target volume.