1. Log Structure 1 2 3 4 5 6 7 8 log index term leader Server 1 command
y = 1 1
y = 9 2
x = 2 3
z = 0 3
y = 7 3
x = 5 3
z = 3
term
leader
Server 1
command 1
x = 3 1
y = 1 1
y = 9 2
x = 2 3
z = 0
Server 2 1
x = 3 1
y = 1 1
y = 9 2
x = 2 3
z = 0 3
y = 7 3
x = 5 3
z = 3
Server 3
followers 1
x = 3 1
y = 1
Server 4 1
x = 3 1
y = 1 1
y = 9 2
x = 2 3
z = 0 3
y = 7 3
x = 5
Server 5
committed entries
CS 190 Lecture Notes: Raft

2. Log Inconsistencies term 1 1 1 4 4 5 5 6 6 6 Server 12 3 4 5 6 7 8 9 10 11 12 1 1 1 4 4 5 5 6 6 6
Server 1
leader for term 8 1 1 1 4 4 5 5 6 6
Server 2 1 1 1 4
Server 3 1 1 1 4 4 5 5 6 6 6 6
Server 4
followers 1 1 1 4 4 5 5 6 6 6 7 7
Server 5 1 1 1 4 4 4 4
Server 6 1 1 1 2 2 2 3 3 3 3 3
Server 7
CS 190 Lecture Notes: Raft

3. When Is It Safe To Commit?
leader 1 2 1 2 1 2 3 1 2 1 2 3 1 2 1 2 1 2 4 1 3 1 2 4 S1 1 2 1 2 1 2 1 3 1 2 4 S2 1 1 1 2 1 3 1 2 4 S3 S4 1 1 1 1 3 1 1 1 3 1 3 1 3 1 3 S5
Term 2
Term 3
Term 4
Term 5
Term 4’
CS 190 Lecture Notes: Raft