Monday, December 04, 2006

How do I failover a Service Group?

You can manually failover a Service Group two ways:

(1) hagrp -switch {Service Group} -to {target node}

(2) hagrp -offline {Service Group} -sys {current node}
hagrp -online {Service Group} -sys {target node}

The second way simply gives you more control. After you offline the Group, you can online it anywhere when you want to. The first way is for an immediate "handsoff" failover.

VCS can automatically failover Groups if you do the following:

(1) Execute "init 6" or "shutdown -ry 0"
(2) Execute "reboot"
(3) Switch off the machine's power
(4) Pull out all heartbeat cables simultaneously
(5) Cause a "fault", i.e. manually shutdown some service or resource in
your Service Group.
(6) Panic the machine.

WARNING: Doing #4 will result in immediate split brain, which may lead to data corruption. Never do this on a production cluster.

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