In the illustration above, the two orange boxes represent two servers that form an HA cluster. The boxes contain the usual components of a Linux™ kernel: file system, buffer cache, disk scheduler, disk drivers, TCP/IP stack and network interface card (NIC) driver. The black arrows illustrate the flow of data between these components.
The orange arrows show the flow of data, as DRBD mirrors the data of a highly available service from the active node of the HA cluster to the standby node of the HA cluster.
We build DRBD clusters for customers who need the aided comfort of an extra mirrored server.