Chapter 2. DRBD Features

Table of Contents

2.1. Single-primary mode
2.2. Dual-primary mode
2.3. Replication modes
2.4. Multiple replication transports
2.5. Efficient synchronization
2.5.1. Variable-rate synchronization
2.5.2. Fixed-rate synchronization
2.5.3. Checksum-based synchronization
2.6. Suspended replication
2.7. On-line device verification
2.8. Replication traffic integrity checking
2.9. Split brain notification and automatic recovery
2.10. Support for disk flushes
2.11. Disk error handling strategies
2.12. Strategies for dealing with outdated data
2.13. Three-way replication
2.14. Long-distance replication with DRBD Proxy
2.15. Truck based replication
2.16. Floating peers

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. Chapter 6, Common administrative tasks 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.