HA-Hobbit with Linux HA 2

[Husemann, Harald]

Hi folks,

as written to the list a few days ago, we're running Hobbit on a Linux 
HA-2 cluster with DRBD. Runs very nice, and the setup is not very 
complicated, so as promised, here are some notes if you like to make 
your Hobbit high available:
(This is more or less a summary of our installation, and not tested but 
written from memory - maybe someone can test it and write a real 
step-by-step guide)

1. Install Linux-HA on both nodes
2. Build a DRBD resource for the Hobbit files, as described in 
http://www.drbd.org/docs/about/
3. Setup a Hobbit group
4. Setup a failover IP resource in the Hobbit group, with a DNS entry if 
you have DNS
5. Install apache, and setup an apache failover resource in the Hobbit 
group for it
6. Setup a colocation constraint, and bind the Hobbit group to the DRBD 
resource
7. Setup an order constraint, to have DRBD started before Hobbit starts
8. Setup a Hobbit user as usual, and link its home directory to the DRBD 
resource. This way, all Hobbit config files, datafiles, etc. are on DRBD 
, and you don't have to fiddle around with syncing the configs etc.
9. Configure Hobbit sources as usual, with some notes:

- Use the failover IP as Hobbit's server IP
- Everywhere you would enter the Hobbitserver's name, enter the name of 
the failover IP (e.g., for the web-based stuff)

10. Try to start Hobbit: It should run as normal.
11. Stop it, switch everything to the other node, and try to start 
Hobbit again. If everything's okay, stop it, and you're ready for the 
final step:

12. Copy the attached script "hobbit" to 
/usr/lib/ocf/resource.d/heartbeat/ ON BOTH NODES

13. Setup a Hobbit resource (e.g. by using the hb_gui and selecting 
"hobbit", which should be visible after a restart of the GUI).

14. Start the Hobbit resource

That's it, now, your Hobbit should be redundant and monitored by the OCF 
  system.

Some final notes:

- Be sure to use the failover IP as BBDISPLAY on all your clients
- NEVER start/stop/restart Hobbit with hobbit.sh, since you could end up 
with two running Hobbit instances (the cluster will see that hobbitd is 
down, and start it itself). reload is (obviously) okay, since it will 
not restart the process.
- If you like to monitor your Hobbit nodes themselves, install a second 
Hobbit (client) instance under a different user (e.g. hobbitmon), which 
is not under cluster control. Without this, only the active node will be 
monitored, since the server (and the client) runs only on this node.

HTH,

hh

-- 
Harald Husemann
Netzwerk- und Systemadministrator
Operation Management Center (OMC)
MATERNA GmbH
Information & Communications

Westfalendamm 98
44141 Dortmund

Geschäftsführer: Dr. Winfried Materna, Helmut an de Meulen, Ralph Hartwig
Amtsgericht Dortmund HRB 5839

Tel: +49 231 9505 222
Fax: +49 231 9505 100
www.annyway.com <http://www.annyway.com/>
www.materna.com <http://www.materna.com/>
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