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Re: gear creation on nodes



Dan's latest change adds some caching of discovered nodes to enable the distribution model for new gears to be faster.  The cache is short, so there's a period where new nodes aren't immediately available.

----- Original Message -----
> 
> 
> I'll let someone jump in and correct if this is wrong but I believe
> the model is still:
> 
> - When a new node is added, it connects to the ActiveMQ topic which
> in turn makes that node respond to MCollective requests
> - All requests for new gears (e.g. new app, scaling, etc) go through
> the broker and for each request the broker queries MCollective for
> the best fit node per the algorithm below
> 
> Given that, when a new node registers with the message bus, it should
> immediately be applicable for new gears. Some caveats if you are
> using custom gear types as the new node would also need to support
> that gear type.
> 
> -Matt
> 
> On 01/28/2013 08:49 PM, Meghdoot wrote:
> 
> 
> 
> Great. Good to know.
> What about node discovery part?
> 
> Sent from my iPhone
> 
> On Jan 28, 2013, at 5:28 PM, Grant Shipley < gshipley redhat com >
> wrote:
> 
> 
> 
> 
> Algorithm for finding an available node
> 
> 
> • Find the district with the most available UUIDs.
> 
> • Find the nodes within that district that have the least
> active_capacity.
> 
> • If some nodes still have active capacity, randomly pick one of the
> nodes with the lower levels of active_capacity.
> 
> • If no nodes in that district have active capacity, find nodes
> within any district (with available UUIDs) that have available
> capacity and randomly pick one of the nodes with the lower levels of
> active_capacity.
> This algorithm means that applications are created on the districts
> with the most available UUIDs first, and districts that have
> available, non-active capacity are preferred.
> 
> 
> 
> 
> --
> gs
> 
> 
> On Jan 28, 2013, at 7:40 PM, meghdoot bhattacharya <
> meghdoot_b yahoo com > wrote:
> 
> 
> 
> 
> 
> Hi,
> Given a set of nodes, when new gears are about to be created, what is
> the algorithm used to select the node?
> 
> 
> If brand new nodes/VM's are added later, how do those new nodes get
> discovered and made available to haproxy for future gear creation on
> those nodes? Does the mcollective in broker periodically send
> messages to discover new nodes or figure out if nodes are gone?
> 
> 
> Thx. _______________________________________________
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> 
> 
> 
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