[[about]]
[preface]
== Please Read This First

This guide is intended to serve users of the Distributed Replicated
Block Device (DRBD) as a definitive reference guide and handbook.

It is being made available to the DRBD community by
http://www.linbit.com/[LINBIT], the project's sponsor company, free of
charge and in the hope that it will be useful. The guide is
constantly being updated.  We try to add information
about new DRBD features simultaneously with the corresponding DRBD
releases. An on-line HTML version of this guide is always available at
http://www.drbd.org/users-guide/.

IMPORTANT: This guide assumes, throughout, that you are using DRBD
version 8.4.0 or later. If you are using a pre-8.4 release of DRBD
, please use the version of this guide which has been
preserved at http://www.drbd.org/users-guide-8.3/.

Some sections in this guide are marked as *Draft*. They have been added
recently, and should not be considered authoritative. Feedback and comments on
these sections are particularly welcome and highly encouraged.

Please use <<s-mailing-list,the drbd-user mailing list>> to submit
comments.

This guide is organized in seven parts:

* <<p-intro>> deals with DRBD's basic functionality. It gives a short
  overview of DRBD's positioning within the Linux I/O stack, and about
  fundamental DRBD concepts. It also examines DRBD's most important
  features in detail.

* <<p-build-install-configure>> talks about building DRBD from
  source, installing pre-built DRBD packages, and contains an overview
  of getting DRBD running on a cluster system.

* <<p-work>> is about managing DRBD, configuring and reconfiguring
  DRBD resources, and common troubleshooting scenarios.

* <<p-apps>> deals with leveraging DRBD to add storage replication and
  high availability to applications. It not only covers DRBD
  integration in the Pacemaker cluster manager, but also advanced LVM
  configurations, integration of DRBD with GFS, and adding high
  availability to Xen virtualization environments.

* <<p-performance>> contains pointers for getting the best performance
  out of DRBD configurations.

* <<p-learn>> dives into DRBD's internals, and also contains pointers
  to other resources which readers of this guide may find useful.

* <<p-appendices>> contains two appendices. <<ap-recent-changes>> is
  an overview of changes in DRBD 8.4, compared to earlier DRBD
  versions. <<ap-man-pages>> contains online versions of the Linux
  manual pages distributed with the latest DRBD version, for reference
  purposes.

Users interested in DRBD training or support services are invited to
contact us at sales@linbit.com or sales_us@linbit.com.
