Added 2nd node to cluster

[Jonathan Bayer]

I've finally gotten my first node up and running. This is on a RHEL6.3
system, I have a script which, once I'm done, I'll post on my blog.

In the meantime, I want to add a 2nd node. Once I've created it and
added it, how do I change the existing VMs to be a DRDB setup so that I
can migrate them from one system to another?

Thanks in advance.


JBB

[Iustin Pop]

Please read the docs at
http://docs.ganeti.org/ganeti/current/html/admin.html?highlight=converting#conversion-of-an-instance-s-disk-type

regards,
iustin

[Kirill Shevchuk]

You will need to run:

# gnt-instance shutdown $instance
# gnt-instance modify -t drbd -n $second_node $instance
# gnt-instance start $instance

for every instance you that you want to convert. There will be
downtime for each instance while data is copied to the second node.

Somewhat riskier way is to run 'gnt-instance modify -t drbd -n
$second_node --no-wait-for-sync $instance' instead. Then you can start
instance earlier before data is fully copied, but you may have worse
performance due to heavy I/O and potentially higher chance of losing
instance data if something goes wrong.

>
> Thanks in advance.
>
>
> JBB

--
Kirill Shevchuk
cyr...@google.com

[Iustin Pop]

Kirill, that's a very nice explanation. Would you take the time to send
a patch against the docs I quoted in the other reply or against the man
pages to make more clear what are the trade-offs?

thanks,
iustin