Which phrase best describes snapshot copies?

Snapshot copies are best described as pointers to blocks on disk. A snapshot captures the state of a system at a specific point in time without duplicating the data. Instead of making a full copy of the data, the snapshot maintains references (or pointers) to the existing data blocks. When a snapshot is created, it records the metadata about the blocks, and any subsequent changes to the data are stored separately, allowing for efficient use of storage space.

This pointer-based mechanism is what allows snapshots to provide a quick recovery option while minimizing the amount of duplicate data that needs to be created and stored. They enable users to revert to previous versions of data efficiently while maintaining the integrity and space optimization of the original data.

In contrast, duplicate copies of blocks on disk would imply that actual copies of the data are created, which is not how snapshots work. Triple-level erasure coding pertains to a data protection scheme that spreads data across multiple locations for redundancy and is unrelated to the concept of snapshots. RAID protection refers to a method of combining multiple disk drives to improve performance and data redundancy, which does not specifically describe how snapshots function.