Make sure that the primary and secondary DRBD servers have the correct host name, and that the host names are unique. You can verify this by using the uname command:

shell> uname -n
drbd-one

If the host name is not set correctly, edit the appropriate file (usually /etc/sysconfig/network, /etc/hostname, or /etc/conf.d/hostname) and set the name correctly.

Each DRBD node must have a unique IP address. Make sure that the IP address information is set correctly within the network configuration and that the host name and IP address has been set correctly within the /etc/hosts file.

Although you can rely on the DNS or NIS system for host resolving, in the event of a major network failure these services may not be available. If possible, add the IP address and host name of each DRBD node into the /etc/hosts file for each machine. This will ensure that the node information can always be determined even if the DNS/NIS servers are unavailable.

As a general rule, the faster your network connection the better. Because the block device data is exchanged over the network, everything that will be written to the local disk on the DRBD primary will also be written to the network for distribution to the DRBD secondary.

For tips on configuring a faster network connection see Section 14.1.3, “Optimizing Performance and Reliability”.

You must have a spare disk or disk partition that you can use as the physical storage location for the DRBD data that will be replicated. You do not have to have a complete disk available, a partition on an existing disk is acceptable.

If the disk is unpartitioned, partition the disk using fdisk, cfdisk or other partitioning solution. Do not create a file system on the new partition.

Remember that you must have a physical disk available for the storage of the replicated information on each DRBD node. Ideally the partitions that will be used on each node should be of an identical size, although this is not strictly necessary. Do, however, ensure that the physical partition on the DRBD secondary is at least as big as the partitions on the DRBD primary node.

If possible, upgrade your system to the latest available Linux kernel for your distribution. Once the kernel has been installed, you must reboot to make the kernel active. To use DRBD you will also need to install the relevant kernel development and header files that are required for building kernel modules. Platform specification information for this is available later in this section.

Kernel header files

Kernel source files

GCC Compiler

glib 2

flex

Tips for Red Hat (including CentOS and Fedora):

Use up2date or yum to update and install the latest kernel and kernel header files:

root-shell> up2date kernel-smp-devel kernel-smp

Reboot. If you are going to build DRBD from source, then update your system with the required development packages:

root-shell> up2date glib-devel openssl-devel libgcrypt-devel glib2-devel \
pkgconfig ncurses-devel rpm-build rpm-devel redhat-rpm-config gcc \
gcc-c++ bison flex gnutls-devel lm_sensors-devel net-snmp-devel \
python-devel bzip2-devel libselinux-devel perl-DBI

If you are going to use the pre-built DRBD RPMs:

root-shell> up2date gnutls lm_sensors net-snmp ncurses libgcrypt glib2 openssl glib

Tips for Debian, Ubuntu, Kubuntu:

Use apt-get to install the kernel packages

root-shell> apt-get install linux-headers linux-image-server

If you are going to use the pre-built Debian packages for DRBD then you should not need any additional packages.

If you want to build DRBD from source, you will need to use the following command to install the required components:

root-shell> apt-get install devscripts flex bison build-essential \
dpkg-dev kernel-package debconf-utils dpatch debhelper \
libnet1-dev e2fslibs-dev libglib2.0-dev automake1.9 \
libgnutls-dev libtool libltdl3 libltdl3-dev

Tips for Gentoo:

Gentoo is a source based Linux distribution and therefore many of the source files and components that you will need are either already installed or will be installed automatically by emerge.

To install DRBD 0.8.x, you must unmask the sys-cluster/drbd build by adding the following line to /etc/portage/package.keywords:

sys-cluster/drbd ~x86
sys-cluster/drbd-kernel ~x86

If your kernel does not already have the userspace to kernelspace linker enabled, then you will need to rebuild the kernel with this option. The best way to do this is to use genkernel with the --menuconfig option to select the option and then rebuild the kernel. For example, at the command line as root:

root-shell> genkernel --menuconfig all

Then through the menu options, select Device Drivers, Connector - unified userspace <-> kernelspace linker and finally press 'y' or 'space' to select the Connector - unified userspace <-> kernelspace linker option. Then exit the menu configuration. The kernel will be rebuilt and installed. If this is a new kernel, make sure you update your bootloader accordingly. Now reboot to enable the new kernel.