Failover Strategies

Question 1

Explain the ‘cold standby’ failover strategy

Answer 1

If a database goes down, you use periodic backups to restore your data on another database/server

Question 2

Explain the pros/cons of the ‘cold standby’ failover strategy

Answer 2

Pros: It’s better than nothing, prevents you from losing all your data. Cheaper option and simple.
Cons: Takes a long time to transfer backup data to new database, you’ll lose any data that wasn’t backed up in the last periodic backup

Question 3

Explain the ‘warm standby’ failover strategy

Answer 3

You have a mirror image of your database that can be instantly ready to take the place of the main database (replication)

Question 4

Explain the pros/cons of the ‘warm standby’ failover strategy

Answer 4

Pros: Near instant switch to backup, little/no data loss, easy to turn on (handled by db platforms)
Cons: More expensive, tiny chance that you might still lose data during the switch to backup

Question 5

Explain the ‘hot standby’ failover strategy

Answer 5

Front end webserver is writing the same data to multiple backup hosts at the same time, so if one host goes down the traffic is immediately routed to another host.

Question 6

Explain the pros/cons of the ‘hot standby’ failover strategy

Answer 6

Pros: most resilient, essentially a horizontal scaling solution
Cons: Most expensive