Open Stack

On August 28, 2014 8:58:11 AM PDT, Clint Byrum <clint at fewbar.com> wrote:
>Excerpts from Jyoti Ranjan's message of 2014-08-27 21:20:19 -0700:
>> I do agree but it create an extra requirement for Undercloud if we
>high
>> availability is important criteria. Because of this, undercloud has
>to be
>> there 24x7, 365 days and to make it available we need to have HA for
>this
>> also. So, you indirectly mean that undercloud also should be designed
>> keeping high availability in mind.
>
>I'm worried that you may be overstating the needs of a typical cloud.
>
>The undercloud needs to be able to reach a state of availability when
>you need to boot boxes. Even if you are doing CD and _constantly_
>rebooting boxes, you can take your undercloud down for an hour, as long
>as it can be brought back up for emergencies.
>
>However, Ironic has already been designed this way. I believe that
>Ironic has a nice dynamic hash ring of server ownership, and if you
>mark a conductor down, the other conductors will assume ownership of
>the machines that it was holding. So the path to making this HA is
>basically "add one more undercloud server."
>
>Ironic experts, please tell me this is true, and not just something I
>inserted into my own distorted version of reality to help me sleep at
>night.

This is correct, HA is achieved in Ironic by having multiple conductors and API servers. It isn't perfect today, but Greg Haynes is working on some of this and it is planned to land in Juno. 

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// jim