Installing And Managing Drbd Services; Understanding Drbd; Installing Drbd Services - Novell LINUX ENTERPRISE SERVER 10 SP2 - STORAGE ADMINISTRATION GUIDE 05-15-2009 Administration Manual

Table of Contents

Installing and Managing DRBD

Services

This section describes how to install, configure, and manage a device-level software RAID 1 across

a network using DRBD* (Distributed Replicated Block Device) for Linux.

Section 9.1, "Understanding DRBD," on page 117

Section 9.2, "Installing DRBD Services," on page 117

Section 9.3, "Configuring the DRBD Service," on page 118

Section 9.4, "Testing the DRBD Service," on page 119

Section 9.5, "Troubleshooting DRBD," on page 120

Section 9.6, "Additional Information," on page 121

9.1 Understanding DRBD

DRBD allows you to create a mirror of two block devices that are located at two different sites

across an IP network. When used with HeartBeat 2 (HB2), DRBD supports distributed high-

availability Linux clusters.

IMPORTANT: The data traffic between mirrors is not encrypted. For secure data exchange, you

should deploy a virtual private network (VPN) solution for the connection.

Data on the primary device is replicated to the secondary device in a way that ensures that both

copies of the data are always identical.

By default, DRBD uses the TCP port 7788 for communications between DRBD nodes.

The open source version of DRBD supports up to 4 TB as maximal overall size of all devices. If you

need a device larger than 4 TB, you can use DRBD+, which is commercially available from Linbit*.

You must set up the DRBD devices before creating file systems on them. Everything to do with user

data should be done solely via the

uses the last 128 MB of the raw device for metadata.

IMPORTANT: Make sure to create file systems only on the

device.

For example, if the raw device is 1024 MB in size, the DRBD device has only 896 MB available for

data, with 128 MB hidden and reserved for the metadata. Any attempt to access the space between

896 MB and 1024 MB fails because it is not available for user data.

9.2 Installing DRBD Services

1 Install the High Availability (HA) pattern on both SUSE Linux Enterprise Servers in your

networked cluster. Installing HA also installs the

1a Log in as the

root

device, not on the raw device, because DRBD

/dev/drbd<n>

user or equivalent, then open YaST.

device, not on the raw

/dev/drbd<n>

program files.

drbd