Linux-HA Release 2 Tutorial

Linux-HA Release 2 Tutorial
Alan Robertson
Project Founder, Project Leader Emeritus –
Linux-HA project
alanr@unix.sh
IBM Systems & Technology Group
Industry Technology Leadership Team
HA Subject Matter Expert
HA BLOG : http://techthoughts.typepad.com/
Linux-HA tutoria –l USENIX/Boston 2008 / 1Tutorial Overview
HA Principles
Installing Linux-HA
Basic Linux-HA configuration
Configuring Linux-HA
Sample HA Configurations
Testing Clusters
Advanced features
Linux-HA tutoria –l USENIX/Boston 2008 / 2Part I
General HA principles
Architectural overview of Linux-HA
Compilation and installation of the Linux-HA
("heartbeat") software
Linux-HA tutoria –l USENIX/Boston 2008 / 3What Is HA Clustering?
Putting together a group of computers which
trust each other to provide a service even
when system components fail
When one machine goes down, others take
over its work
This involves IP address takeover, service
takeover, etc.
New work comes to the “takeover” machine
Not primarily designed for high-performance
Linux-HA tutoria –l USENIX/Boston 2008 / 4What Can HA Clustering Do For You?
It cannot achieve 100% availabilit y– nothing
can.
HA Clustering designed to recover from single faults
It can make your outages very short
From about a second to a few minutes
It is like a Magician's (Illusionist's) trick:
When it goes well, the hand is faster than the eye
When it goes not-so-well, it can be reasonably visible
A good HA clustering system adds a “9” to your base ...