Two-phase snap copy
    1.
    发明授权
    Two-phase snap copy 有权
    两相快照

    公开(公告)号:US07493458B1

    公开(公告)日:2009-02-17

    申请号:US10941671

    申请日:2004-09-15

    IPC分类号: G06F12/00

    摘要: A point in time copy of a data set is provided using a two-phase snapshot copy operation. When a write request is received, as part of the first phase, a chunk including the target location of the write request is determined. Using a “copy on first write” technique, the data at the target location is copied to a snap data area in an allocated data area that is the size of the chunk. A first map for the data set is updated to include up to three entries representing a mapping of the segment including the target location. A second map for the snap data area is updated to include a single entry for the copy of the data from the target location. As part of the second phase, the multiple entries in the first map are coalesced into a single entry after the remaining portions of the chunk are copied to the data area in the snap data area.

    摘要翻译: 使用两相快照复制操作提供数据集的时间点副本。 当接收到写请求时,作为第一阶段的一部分,确定包括写请求的目标位置的块。 使用“第一次写入复制”技术,将目标位置的数据复制到作为块大小的分配数据区域中的快照数据区域。 数据集的第一个映射被更新为包括最多三个表示包括目标位置的段的映射的条目。 快照数据区域的第二张地图被更新为包含来自目标位置的数据副本的单个条目。 作为第二阶段的一部分,在块的剩余部分被复制到快照数据区域中的数据区域之后,第一个地图中的多个条目合并成一个条目。