1. Storage System

Goal: Building Fault-Tolerance Storage

app is stateless, but storage hold persistent state

1.1 Why Hard

• High performance ⇒ Shard data across servers
• Many servers ⇒ Constant faults
• Fault tolerance ⇒ Replications
• Replications ⇒ Potential inconsistency
• Strong consisteny ⇒ low performance

1.2 Ideal Consistency

Behave as if single system

2. GFS

• Designed for high performanced.
• Use Replication + Fault Tolerance
• Successful system
  • Not standard
    • Single Master
    • inconsistency possible

2.1 Properties

• Big → large data set