Patent ID: 9335931
Filing Date: 2016-05-10
CPC Classification: G06F

Claim Text:
1. A method for making a snapshot of a volume, the method comprising: receiving a write access attempt for the volume; determining whether a snapshot of the volume is being taken; based on a determination that a snapshot of the volume is being taken, buffering information associated with the write access attempt in a buffer; updating a snapshot indicator in accordance with the information associated with the write access attempt, wherein the snapshot indicator comprises block information regarding a block in the volume that is a target of the write access attempt, wherein the snapshot indicator is stored in a snapshot bitmap; also based on the determination that the snapshot of the volume is being taken, updating a buffer indicator in accordance with the information associated with the write access attempt, wherein the buffer indicator indicates whether the block in the volume that is the target of the write access attempt was accessed while the snapshot of the volume was being taken, and wherein the buffer indicator is stored in a buffer bitmap separate from the snapshot bitmap; receiving a new write access attempt for the volume after the write access attempt; using a new snapshot indicator, a new buffer, and a new buffer indicator for the buffering, the updating the snapshot indicator, and the updating the buffer indicator for the new write access attempt, wherein the new snapshot indicator is stored in a new snapshot bitmap separate from the snapshot bitmap and the buffer bitmap, and wherein the new buffer indicator is stored in a new buffer bitmap separate from the buffer bitmap and the snapshot bitmap; receiving a read access attempt after receiving the new write access attempt; and fulfilling the read access attempt using the snapshot bitmap, the new snapshot bitmap, the buffer indicator, and the new buffer indicator.