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From aaron morton <aa...@thelastpickle.com>
Subject Re: seed faq
Date Sun, 24 Apr 2011 02:53:19 GMT
May also want to add that seed nodes do not auto bootstrap.

Thanks
Aaron
On 22 Apr 2011, at 13:24, Maki Watanabe wrote:

> Thank you, Naren.
> I'll add some more details and upload it to FAQ wiki page.
> 
> maki
> 
> 2011/4/21 Narendra Sharma <narendra.sharma@gmail.com>:
>> Here are some more details that might help:
>> 1. You are right that Seeds are referred on startup to learn about the ring.
>> 2. It is a good idea to have more than 1 seed. Seed is not SPoF. Remember
>> Gossip also provides eventual consistency. So if seed is missing, the new
>> node may not have the correct view of the ring. However, after talking to
>> other nodes it will eventually have the uptodate state of the ring.
>> 3. In an iteration Gossiper on a node sends gossip message
>>  - To a known live node (picked randomly)
>>  - To a known dead node (based on some probability)
>>  - To a seed node (based on some probability)
>> 
>> Thanks,
>> Naren
>> On Wed, Apr 20, 2011 at 7:13 PM, Maki Watanabe <watanabe.maki@gmail.com>
>> wrote:
>>> 
>>> I made self answered faqs on seed after reading the wiki and code.
>>> If I misunderstand something, please point out to me.
>>> 
>>> == What are seeds? ==
>>> 
>>> Seeds, or seed nodes are the nodes which new nodes refer to on
>>> bootstrap to know ring information.
>>> When you add a new node to ring, you need to specify at least one live
>>> seed to contact. Once a node join the ring, it learns about the other
>>> nodes, so it doesn't need seed on subsequent boot.
>>> 
>>> There is no special configuration for seed node itself. In stable and
>>> static ring, you can point non-seed node as seed on bootstrap though
>>> it is not recommended.
>>> Nodes in the ring tend to send Gossip message to seeds more often by
>>> design, so it is probable that seeds have most recent and updated
>>> information of the ring. ( Refer to [[ArchitectureGossip]] for more
>>> details )
>>> 
>>> == Does single seed mean single point of failure? ==
>>> 
>>> If you are using replicated CF on the ring, only one seed in the ring
>>> doesn't mean single point of failure. The ring can operate or boot
>>> without the seed. But it is recommended to have multiple seeds in
>>> production system to maintain the ring.
>>> 
>>> 
>>> 
>>> Thanks
>>> --
>>> maki
>> 
>> 
>> 
>> --
>> Narendra Sharma
>> Solution Architect
>> http://www.persistentsys.com
>> http://narendrasharma.blogspot.com/
>> 
>> 


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