User data increases as businesses grow. The copy reuse function provided by the CDM solution allows users to mining larger value of data directly on DR systems. During copy reuse, level-2 copies are generated based on snapshots and are used for other purposes such as data analysis and test. This does not change the original snapshots. The original snapshots can be used for data recovery. Moreover, changes to snapshots and level-2 snapshot copies do not lead to mutual impact, making operations more flexible.
Context
A level-2 copy of a snapshot is not a complete entity data, but a virtual copy that is generated based on the original snapshot and can be read and written. To prevent impact on production performance and networking, data at the DR site is preferentially repurposed. Figure 1 shows the reuse process.
- If a read request to a level-2 copy is to read the data of the original snapshot, the request is directed to the space pointed by the original snapshot to read data.
- Write operations on a level-2 copy, that is pre-write copy operations, change the data pointed by the copy only, to ensure the original snapshot data remains unchanged.
If a data LUN has multiple snapshots but one level-2 copy, the pre-write copy operation will be performed only once when you initiate write requests to data blocks during copy reuse.