Databases Reference
In-Depth Information
CHAPTER 9
Replication
Perhaps the most important job of any MongoDB administrator is making sure that
replication is set up and functioning correctly. Use of MongoDB's replication func-
tionality is always recommended in production settings, especially since the current
storage engine does not provide single-server durability (see
Appendix C
for details).
Replicas can be used purely for failover and data integrity, or they can be used in more
advanced ways, such as for scaling out reads, taking hot backups, or as a data source
for offline batch processing. In this chapter, we'll cover everything you need to know
about replication.
Master-Slave Replication
Master-slave replication is the most general replication mode supported by MongoDB.
This mode is very flexible and can be used for backup, failover, read scaling, and more
(see Figures
9-1
and
9-2
).
Figure 9-1. A master with one slave
