DRBD

DRBD (or Distributed Replicated Block Device) is a network block device that provides reliability when storing data across multiple network nodes.

From the kernel documentation: "DRBD is a shared-nothing, synchronously replicated block device. It is designed to serve as a building block for high availability clusters and in this context, is a 'drop-in' replacement for shared storage. Simplistically, you could see it as a network RAID 1."

Emerge
Install :

This package installs the userland utilities to interact with, and control DRBD.

aka 'drbdsetup' and 'drbdadm'

Drbd's documentation repository
To use drbd's pdfs you must register and login.

drbd's pdf documentation repository

drbd's management gui
Drbd has a utility to easily setup a cluster in 10 minutes. drbd's management gui

Errors
"ERROR: unknown cs for drbd0 : BrokenPipe, Update/DUnknown"

This error means connection state has a problem, link needs fixing, or drbd version updating. Upstream states "we had some issues with discarding the first successful connection and getting in a connect/brokenpipe loop."

Run this command to extract useful information.

External resources

 * The DRBD User’s Guide
 * 8.3 change logs
 * 8.4 change logs