The Alibaba Cloud distributed File System provides stable and efficient data access and reliability for ECS. Triplicate technology, that is, the process of triple replication of data, is the priciple concept designed by Alibaba Cloud and implemented in the Distributed File System.

Chunks

The Distributed File System of Alibaba Cloud uses a flat design in which a linear address space is divided into slices, also called chunks. Each chunk has three copies stored on different server nodes on different racks. This guarantees data reliability.

For the data on the cloud disk, all user operations, including addition, modification, and deletion of data, are synchronized to the three copies. This mode guarantees the reliability and consistency of user data.



How triplicate technology works

Triplicate technology involves three key components: Master, Chunk Server, and Client. To demonstrate how triplicate technology works, in this example, the write operation of an ECS user undergoes several conversions before being executed by the Client. The process is as follows:

  1. The Client determines the location of a chunk corresponding to one of your write operations.
  2. The Client sends a request to the Master to query the storage locations (that is, the Chunk Servers) of the three copies of the chunk.
  3. The Client sends write requests to the corresponding three Chunk Servers according to the results returned from the Master.
  4. The Client returns a message to the user indicating whether the operation was successful.

This strategy guarantees that all the copies of a chunk are distributed on different Chunk Servers on different racks, effectively reducing the potential of total data loss caused by failure of a Chunk Server or a rack.

Data protection

If a system failure occurs because of a corrupted node or hard drive failure, some chunks may lose one or more of the three valid chunk copies associated with them. If this occurs and triplicate technology is enabled, the Master replicates data between Chunk Servers to reinstate the missing chunk copies across different nodes.

Triplicate technology is strongly recommended to be used in conjunction with other data protection means, such as regular data backups or snapshots. Make sure that all appropriate actions are implemented to protect your data and guarantee its availability.