Article Source

• Title: DISTRIBUTED SYSTEMS Concepts and Design Fifth Edition
• Authors: George Coulouris, Jean Dollimore, Tim Kindberg and Gordon Blair

Overview of Data Storage and Coordination Services

We now present the three services that together provide data and coordination services to higher-level applications and services: the Google File System, Chubby and Bigtable. These are complementary services in the Google infrastructure:

• The Google File System is a distributed file system offering a similar service to NFS and AFS, as discussed in Chapter 12 [1]. It offers access to unstructured data in the form of files, but optimized to the styles of data and data access required by Google (very large files, for example).

• Chubby is a multi-faceted service supporting, for example, coarse-grained distributed locking for coordination in the distributed environment and the storage of very small quantities of data, complementing the large-scale storage offered by the Google File System.

• Bigtable offers access to more structured data in the form of tables that can be indexed in various ways including by row or column. Bigtable is therefore a style of distributed database, but unlike many databases it does not support full relational operators (these are viewed by Google as unnecessarily complex and unscalable ).

These three services are also interdependent. For example, Bigtable uses the Google File System for storage and Chubby for coordination.

References

[1] George Coulouris, Jean Dollimore, Tim Kindberg and Gordon Blair, DISTRIBUTED SYSTEMS Concepts and Design Fifth Edition, Pearson Education, Inc., 2012.