There are 4 main types of clusters:

- Storage
- High Availability (HA)
- Load Balancing
- High Performance

Allows servers to simultaniously read and write to a single shared filesystem.
Example Red Hat Cluster Suite (RHCS) storage cluster is GFS
This cluster simplifies storage administration by limiting the installation and patching of applications to one filesystem.
Eliminates the need for redundant copies of application data and simplifies backup and disaster recover.

https://www.centos.org/docs/5/html/Cluster_Suite_Overview/s1-clstr-basics-CSO.html