PiT copy; Snapshot
A point-in-time copy is a copy of original data as it appeared at a point in time. In a conventional backup operation, users often create a PiT Copy, while an application is in quiescing, to make the PiT Copy a consistent copy of original data.
There are two popular implementation techniques for creating PiT Copies inside a storage system: split mirror and copy on write.
Split mirror is a technique for replicating the original data at a point in time. In some implementations, a storage system replicates the original data, and when users create the PiT Copy, a storage system splits the replication. Copy on Write (CoW) is a technique for capturing data changes to storage and creating a PiT Copy after specifying the point in time. In some implementations, when users create the PiT Copy, a storage system creates its image with both the original data and the modified data.
Techniques for creating PiT Copies have a trade-off between occupied...
- 1.Alain Azagury, et al. Point-in-time copy: yesterday, today, and tomorrow. In: Proceedings of the IEEE Symposium Conference on Mass Storage Systems and Technologies; 2002.Google Scholar