fuel-dev team mailing list archive

[Roman Alekseenkov <ralekseenkov@xxxxxxxxxxxx>]

Dmitry,

You are welcome to create a pull request against the documentation to make
it more precise.

Thanks,
Roman

On Friday, January 10, 2014, Dmitriy Novakovskiy wrote:

> Thanks guys. That helped a lot.
>
> ---
> Regards,
> Dmitriy
>
>
> On Fri, Jan 10, 2014 at 5:44 AM, Miroslav Anashkin <manashkin@xxxxxxxxxxxx
> > wrote:
>
> Hi Dmitriy,
>
> A1. Yes, MySQL+Galera is true master-master solution. While it is possible
> and, in case of 6+ nodes even recommended, to set 1-2 Galera nodes as
> slaves - for additional data consistency.
> Previous Fuel versions use HAProxy as MySQL managing solution.
> In case of Mirantis OpenStack (starting from 3.0 or 3.1) MySQL+Galera
> cluster is managed by Pacemaker.
> There is no single master node in Galera cluster at all - there are nodes
> with most recent data replica and nodes which still have to sync with this
> recent replica.
> Workflow is simple. Node serves new data changing request and increases
> its UUID number. All the other nodes must synchronize data with all the
> nodes with UUID greater than current.
>
> A2. Yes, CEPH monitors are also master-master.  One of them is
> periodically becomes a leader. Leader is the node, which got the most
> recent cluster map replica first. Other monitor nodes must sync they
> cluster map with current leader. Every monitor node already synced with
> leader becomes provider and leader knows which nodes are currently
> providers. So, leader also tells the other nodes which provider each of
> them should use to get data from.
> CEPH monitor synchronization algorithm works similar way as Galera, but
> CEPH nodes are parted by functionality to monitor nodes and data storage
> nodes. In turn, every Galera node has all the same service set on each node.
> So, CEPH monitor nodes only manage where the data should be actually
> stored and maintain data consistency between OSD nodes.
>
>
> A3. Additionally to the previous answerers I may add that Neutron is a
> router among the other functionality. It is the reason why there are single
> entry points.
>
>
> On Fri, Jan 10, 2014 at 12:18 PM, Dmitriy Novakovskiy <
> dnovakovskiy@xxxxxxxxxxxx> wrote:
>
> Hi guys,
>
> I'm currently kicking off a a project with new customer, and stumbled on
> some holes in my understanding of Mirantis HA architecture.
>
> Can you please help me understand the following:
>
> Q1. MySQL + Galera - is it an active/active HA? I was told/tend to think
> "yes", but want to understand it better. A simple workflow example would
> help
>
> Q2. ceph-mon on controllers - same question as Q1
>
> Q3. Neutron - is it in active/standy HA? I got this understanding from
> docs and want to understand why. I was told that Grizzly and Havanna
> support multiple l3 agents, but we don't leverage it on some reason in Fuel.
>
> Thanks a lot in advance
>
> ---
> Regards,
> Dmitriy
>
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>
>
>
> --
>
> *Kind Regards*
>
> *Miroslav Anashkin**L2 support engineer**,*
> *Mirantis Inc.*
>
>