Chapter 2. DRBD Features

This chapter discusses various useful DRBD features, and gives some background information about them. Some of these features will be important to most users, some will only be relevant in very specific deployment scenarios. Part III, “Working with DRBD” and Chapter 7, Troubleshooting and error recovery contain instructions on how to enable and use these features in day-to-day operation.

2.1. Single-primary mode

In single-primary mode, a resource is, at any given time, in the primary role on only one cluster member. Since it is guaranteed that only one cluster node manipulates the data at any moment, this mode can be used with any conventional file system (ext3, ext4, XFS etc.).

Deploying DRBD in single-primary mode is the canonical approach for High-Availability (fail-over capable) clusters.