Failover manual process in Redis - Step-by-Step Execution

Concept Flow - Failover manual process

Detect Master Failure

↓

Promote Slave to Master

↓

Update Clients to New Master

↓

Reconfigure Other Slaves

↓

Monitor New Master

↓

END

This flow shows the steps to manually handle failover in Redis by detecting failure, promoting a slave, updating clients, reconfiguring slaves, and monitoring.

Execution Sample

Redis

1. Check master status
2. Promote slave with 'SLAVEOF NO ONE'
3. Point clients to new master
4. Reconfigure other slaves
5. Monitor new master health

This sequence manually switches Redis roles to recover from master failure.

Execution Table

Step	Action	Command/Operation	Result/State Change
1	Detect Master Failure	Ping master or check logs	Master is unresponsive
2	Promote Slave to Master	SLAVEOF NO ONE on slave	Slave becomes new master
3	Update Clients	Change client config to new master IP	Clients connect to new master
4	Reconfigure Other Slaves	SLAVEOF new_master_ip on other slaves	Slaves replicate new master
5	Monitor New Master	Regular PING and logs	Ensure new master is stable
6	END	Manual failover complete	System running with new master

💡 Manual failover ends after new master is stable and clients are updated

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
Master Status	Responsive	Unresponsive	N/A	N/A	N/A	N/A
Slave Role	Slave	Slave	Master	Master	Master	Master
Client Connection	Master IP	Master IP	Master IP	New Master IP	New Master IP	New Master IP
Other Slaves Role	Slave	Slave	Slave	Slave	Slave of new master	Slave of new master

Key Moments - 3 Insights

Why do we run 'SLAVEOF NO ONE' on the slave?

Running 'SLAVEOF NO ONE' stops the slave from replicating and promotes it to master, as shown in execution_table step 2.

Why must clients be updated after promoting the new master?

Clients need to connect to the new master IP to read/write data correctly, as shown in execution_table step 3.

What happens if other slaves are not reconfigured?

They will still replicate the old master, causing data inconsistency. Step 4 shows reconfiguration to replicate the new master.

Visual Quiz - 3 Questions

Look at the execution_table, what command is used to promote a slave to master?

A SLAVEOF NO ONE

B SLAVEOF master_ip

C PING master

D CONFIG REWRITE

💡 Hint

Check step 2 in the execution_table where the slave is promoted.

At which step do clients start connecting to the new master?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look at the 'Update Clients' action in the execution_table.

If the master is still responsive, what happens to the failover process?

A Clients update to new master

B Failover proceeds anyway

C Failover stops at step 1

D Slaves reconfigure

💡 Hint

Refer to the 'Detect Master Failure' step in execution_table and variable_tracker for Master Status.

Concept Snapshot

Failover manual process in Redis:
1. Detect master failure by pinging.
2. Promote a slave with 'SLAVEOF NO ONE'.
3. Update clients to new master IP.
4. Reconfigure other slaves to replicate new master.
5. Monitor new master health continuously.

Full Transcript

In Redis manual failover, first detect if the master is down by pinging or checking logs. If unresponsive, promote a slave to master by running 'SLAVEOF NO ONE' on it. Then update all clients to connect to this new master. Next, reconfigure other slaves to replicate from the new master. Finally, monitor the new master to ensure stability. This process ensures Redis continues working despite master failure.