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Posted to users@activemq.apache.org by sekaijin <je...@sap.aphp.fr> on 2016/05/01 16:37:38 UTC
Re: clustering architecture
Hi
There is a little thing I do not understand in the election of the master.
I have two geographic site (Paris, Versailles).
the quorum is (n / 2) +1
if I have two servers in each site
the quorum is (4/2) +1 = 3
so if I have a blackout on the site (eg fire) I do not have the quorum
because I have only two servers
if I have two server on a site and on the other
the quorum is (3/2) +1 = 2
so if I have a blackout on first site (eg fire) I do not have a quorum
because I have only one server
It is impossible to secure the cluster?
A+JYT
--
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Re: clustering architecture
Posted by Tim Bain <tb...@alumni.duke.edu>.
Please start a new email thread, with a new subject, for any questions you
want answered. Hijacking someone else's thread where they're trying to get
answers to their own questions is impolite.
Tim
On May 4, 2016 6:34 AM, "Jstaceyss" <Je...@gmail.com>
wrote:
> Tim,
>
> I'm not sure if you can help but this site with jms codes is ruining my
> life. The responsibility of the actions of others is not being taken.
> Please stop it. I am beginning to beg for help
> On May 2, 2016 11:46 PM, "Tim Bain [via ActiveMQ]" <
> ml-node+s2283324n4711461h93@n4.nabble.com> wrote:
>
> > It's not possible to have a quorum (i.e. > 50%) in all scenarios when you
> > only have two groupings and both of them could disappear entirely. By
> > definition, to have a quorum after the loss of one grouping, the lost
> > grouping must be < 50% and the one that remains must be > 50%, so in the
> > inverse situation you can't possibly have a quorum. This is why three is
> > typically the number used to ensure survivability of the loss of a single
> > item (whether an "item" is a process, a host, a rack, or a datacenter).
> > So
> > either you need a third datacenter in a third location, or you need to
> put
> > two groupings in a single geographic site (in separate buildings, for
> > example, or different floors or rooms, or on the other side of town), and
> > accept that you're sacrificing the ability to survive certain
> catastrophes
> > in order to save the cost of locating the third datacenter somewhere
> > geographically distant.
> >
> > Tim
> >
> > On Sun, May 1, 2016 at 8:37 AM, sekaijin <[hidden email]
> > <http:///user/SendEmail.jtp?type=node&node=4711461&i=0>>
> > wrote:
> >
> > > Hi
> > >
> > > There is a little thing I do not understand in the election of the
> > master.
> > >
> > > I have two geographic site (Paris, Versailles).
> > > the quorum is (n / 2) +1
> > > if I have two servers in each site
> > > the quorum is (4/2) +1 = 3
> > > so if I have a blackout on the site (eg fire) I do not have the quorum
> > > because I have only two servers
> > >
> > > if I have two server on a site and on the other
> > > the quorum is (3/2) +1 = 2
> > > so if I have a blackout on first site (eg fire) I do not have a quorum
> > > because I have only one server
> > >
> > > It is impossible to secure the cluster?
> > >
> > > A+JYT
> > >
> > >
> > >
> > > --
> > > View this message in context:
> > >
> >
> http://activemq.2283324.n4.nabble.com/clustering-architecture-tp4711412p4711418.html
> > > Sent from the ActiveMQ - User mailing list archive at Nabble.com.
> > >
> >
> >
> > ------------------------------
> > If you reply to this email, your message will be added to the discussion
> > below:
> >
> >
> http://activemq.2283324.n4.nabble.com/clustering-architecture-tp4711412p4711461.html
> > To start a new topic under ActiveMQ - User, email
> > ml-node+s2283324n2341805h57@n4.nabble.com
> > To unsubscribe from ActiveMQ - User, click here
> > <
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> >
> > .
> > NAML
> > <
> http://activemq.2283324.n4.nabble.com/template/NamlServlet.jtp?macro=macro_viewer&id=instant_html%21nabble%3Aemail.naml&base=nabble.naml.namespaces.BasicNamespace-nabble.view.web.template.NabbleNamespace-nabble.view.web.template.NodeNamespace&breadcrumbs=notify_subscribers%21nabble%3Aemail.naml-instant_emails%21nabble%3Aemail.naml-send_instant_email%21nabble%3Aemail.naml
> >
> >
>
>
>
>
> --
> View this message in context:
> http://activemq.2283324.n4.nabble.com/clustering-architecture-tp4711412p4711543.html
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Re: clustering architecture
Posted by Jstaceyss <Je...@gmail.com>.
Tim,
I'm not sure if you can help but this site with jms codes is ruining my
life. The responsibility of the actions of others is not being taken.
Please stop it. I am beginning to beg for help
On May 2, 2016 11:46 PM, "Tim Bain [via ActiveMQ]" <
ml-node+s2283324n4711461h93@n4.nabble.com> wrote:
> It's not possible to have a quorum (i.e. > 50%) in all scenarios when you
> only have two groupings and both of them could disappear entirely. By
> definition, to have a quorum after the loss of one grouping, the lost
> grouping must be < 50% and the one that remains must be > 50%, so in the
> inverse situation you can't possibly have a quorum. This is why three is
> typically the number used to ensure survivability of the loss of a single
> item (whether an "item" is a process, a host, a rack, or a datacenter).
> So
> either you need a third datacenter in a third location, or you need to put
> two groupings in a single geographic site (in separate buildings, for
> example, or different floors or rooms, or on the other side of town), and
> accept that you're sacrificing the ability to survive certain catastrophes
> in order to save the cost of locating the third datacenter somewhere
> geographically distant.
>
> Tim
>
> On Sun, May 1, 2016 at 8:37 AM, sekaijin <[hidden email]
> <http:///user/SendEmail.jtp?type=node&node=4711461&i=0>>
> wrote:
>
> > Hi
> >
> > There is a little thing I do not understand in the election of the
> master.
> >
> > I have two geographic site (Paris, Versailles).
> > the quorum is (n / 2) +1
> > if I have two servers in each site
> > the quorum is (4/2) +1 = 3
> > so if I have a blackout on the site (eg fire) I do not have the quorum
> > because I have only two servers
> >
> > if I have two server on a site and on the other
> > the quorum is (3/2) +1 = 2
> > so if I have a blackout on first site (eg fire) I do not have a quorum
> > because I have only one server
> >
> > It is impossible to secure the cluster?
> >
> > A+JYT
> >
> >
> >
> > --
> > View this message in context:
> >
> http://activemq.2283324.n4.nabble.com/clustering-architecture-tp4711412p4711418.html
> > Sent from the ActiveMQ - User mailing list archive at Nabble.com.
> >
>
>
> ------------------------------
> If you reply to this email, your message will be added to the discussion
> below:
>
> http://activemq.2283324.n4.nabble.com/clustering-architecture-tp4711412p4711461.html
> To start a new topic under ActiveMQ - User, email
> ml-node+s2283324n2341805h57@n4.nabble.com
> To unsubscribe from ActiveMQ - User, click here
> <http://activemq.2283324.n4.nabble.com/template/NamlServlet.jtp?macro=unsubscribe_by_code&node=2341805&code=SmVubmlmZXJzdGFjZXlzb3V0aGFyZEBnbWFpbC5jb218MjM0MTgwNXwtMTM1MDkyOTA0Nw==>
> .
> NAML
> <http://activemq.2283324.n4.nabble.com/template/NamlServlet.jtp?macro=macro_viewer&id=instant_html%21nabble%3Aemail.naml&base=nabble.naml.namespaces.BasicNamespace-nabble.view.web.template.NabbleNamespace-nabble.view.web.template.NodeNamespace&breadcrumbs=notify_subscribers%21nabble%3Aemail.naml-instant_emails%21nabble%3Aemail.naml-send_instant_email%21nabble%3Aemail.naml>
>
--
View this message in context: http://activemq.2283324.n4.nabble.com/clustering-architecture-tp4711412p4711543.html
Sent from the ActiveMQ - User mailing list archive at Nabble.com.
Re: clustering architecture
Posted by Tim Bain <tb...@alumni.duke.edu>.
It's not possible to have a quorum (i.e. > 50%) in all scenarios when you
only have two groupings and both of them could disappear entirely. By
definition, to have a quorum after the loss of one grouping, the lost
grouping must be < 50% and the one that remains must be > 50%, so in the
inverse situation you can't possibly have a quorum. This is why three is
typically the number used to ensure survivability of the loss of a single
item (whether an "item" is a process, a host, a rack, or a datacenter). So
either you need a third datacenter in a third location, or you need to put
two groupings in a single geographic site (in separate buildings, for
example, or different floors or rooms, or on the other side of town), and
accept that you're sacrificing the ability to survive certain catastrophes
in order to save the cost of locating the third datacenter somewhere
geographically distant.
Tim
On Sun, May 1, 2016 at 8:37 AM, sekaijin <je...@sap.aphp.fr>
wrote:
> Hi
>
> There is a little thing I do not understand in the election of the master.
>
> I have two geographic site (Paris, Versailles).
> the quorum is (n / 2) +1
> if I have two servers in each site
> the quorum is (4/2) +1 = 3
> so if I have a blackout on the site (eg fire) I do not have the quorum
> because I have only two servers
>
> if I have two server on a site and on the other
> the quorum is (3/2) +1 = 2
> so if I have a blackout on first site (eg fire) I do not have a quorum
> because I have only one server
>
> It is impossible to secure the cluster?
>
> A+JYT
>
>
>
> --
> View this message in context:
> http://activemq.2283324.n4.nabble.com/clustering-architecture-tp4711412p4711418.html
> Sent from the ActiveMQ - User mailing list archive at Nabble.com.
>