Overview
The primary objective of this practical course is to introduce the Linux high-availability stack (Pacemaker, DRBD) to system administrators. During the training, each participant will build a two-machine cluster that offers a simple highly-available service (such as PostgreSQL or NFS) on a virtual IP address. Also, uses of DRBD not related to high availability are considered.
Requirements
- General understanding of Linux block devices, filesystems, and TCP/IP networking
- For the “Root filesystem on DRBD” topic: perfect understanding how a Linux system boots (initramfs, init, services, runlevels, …)
Course Outline
- DRBD basics
- Theory of operation
- Installation
- Supported replication modes and their use cases
- Creation of a two-node single-primary cluster
- Manual failover
- Recovering from split-brain
- Corosync
- Installation and initial configuration
- Pacemaker
- Theory of operation
- Installation
- Role of STONITH devices
- Configuration of resource agents
- DRBD
- Mounted filesystem
- Virtual IP address
- LSB and systemd services
- Groups, ordering and colocation constraints
- DRBD in Dual-Primary mode
- Use with OCFS2
- Advanced topic: root filesystem on DRBD