(3) Single master: Google embraced the concept of a single master in their distributed system as a valuable tool to simplify the design and make it more straightforward.
Currently GFS uses one master per cell [21], with multiple cells per data center.
Even though Google has worked around the issue this case underscores the importance of scalability and the limitation of assigning different levels of responsibility in any distributed system that is expected to scale.
The biggest weakness in this system that, the Master can be the single point of failure.
However, this can be overcome by replicating the master state.
The ‘‘Shadow Masters’’ can provide read-only access in the absence of primary master