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From Maki Watanabe <watanabe.m...@gmail.com>
Subject Re: seed faq
Date Fri, 22 Apr 2011 01:24:32 GMT
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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