Although data matches on mirrored slices or synchronized master volumes and proxy volumes, the purposes of use are different.
Mirrored slices are equal one another, and their purpose is to maintain data redundancy in order to provide continuous access as long as any normal slice remains even if an error occurs in one of the slices.
However, even if the master volume and the proxy volume are synchronized, they are separate volumes and not equals. You may consider the master the primary volume, and the proxy the secondary volume. This means that you cannot continue accessing a master volume where all slices comprising the master volume are abnormal even if proxy volumes are normal. The purpose of proxy volumes is to create snapshots (saved copies from the master volume at certain moment) for a different service running concurrently with the primary service but not to improve the data redundancy of the master volume used in the primary service.
While the function of GDS Snapshot creating snapshots by detaching slices is a by-product of mirroring, the function itself is the primary purpose of GDS Snapshot by proxy volumes. Therefore, the application of proxy volumes provides more flexible disk configurations and service styles for snapshot management.
