DRBD - disk mirroring via IP

Philipp Reisner

HA Clusters (in Failover configuration) are common practice when a server with mirrored disks (RAID) cannot offer the desired availability for the application. HA Clusters can offer better availability because they can mask failures other than hard disk failures.

DRBD is a device driver for Linux which allows you to build clusters with distributed mirrors, so-called "shared nothing" clustering. This architecture does not only have the advantage that the physical distance between the two copies of the data can be magnitudes greater than with RAID sets, but it is also (magnitudes) cheaper than clusters with shared disks.

DRBD is currently available for Linux-2.2 and Linux-2.4, provides reasonable performance on reasonable hardware and is on its way into data centers and embedded applications.