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From Aaron Morton <aa...@thelastpickle.com>
Subject Re: If one seed node crash, how can I add one seed node?
Date Wed, 08 Dec 2010 20:21:14 GMT
1. Ideally yes, but the system will work if they are not. 
2. No. Once the node is down they will stop sending requests to it, and gossip is designed
to test down nodes to see if they are back up.

Aaron

On 09 Dec, 2010,at 04:54 AM, lei liu <liulei412@gmail.com> wrote:


Thanks all,
I have three questions:
1. Must seed list be identical on all nodes ?
2. If one seed node crash, all node will communication with the failure seed node, I think
this is harm for all nodes, isn't it?if this yes, how I can replace the failure seed node
in all node? 

 

2010/12/8 Jonathan Ellis <jbellis@gmail.com>
"Two seeds per datacenter" is my rule of thumb.

On Tue, Dec 7, 2010 at 3:07 PM, Eric Gilmore <eric@riptano.com> wrote:

What would comprise a sane and reasonably balanced list?  Should there be a certain proportion
of seeds per total nodes?  Any other considerations besides a) list must be identical on
all nodes and b) you can't auto-bootstrap a seed node?

I'm new to thinking about this setting, but it sounds like this discussion may be approaching
some best-practice guidelines.



On Tue, Dec 7, 2010 at 1:01 PM, Jonathan Ellis <jbellis@gmail.com> wrote:
The gossip-to-seed each round is to prevent cluster partitions, so if you're following correct
procedure and making every node's seed list identical, then any potential new nodes gossiping
to one of the old seeds means it is still harmless for old nodes not to gossip to the new
one until the next restart.



On Tue, Dec 7, 2010 at 2:10 PM, Aaron Morton <aaron@thelastpickle.com> wrote:
Ryan, 
I've not checked with the code but the wiki docs for the Gossip Protocol say it makes use
of the seed list. http://wiki.apache.org/cassandra/ArchitectureGossip


During each gossip round a node will try to gossip to one seed node. 

Which made me think keeping the list sane and reasonably balanced was a good idea. Obviously
would not matter too much on a small cluster though. 

Aaron



On 08 Dec, 2010,at 07:16 AM, Ryan King <ryan@twitter.com> wrote:

Note that there's not really anything special about the seed node and its all relative–
the cluster doesn't necessarily have to agreed on who the seeds are.

So, to bring up a new node to replace the old seed, just set the new node's seed to any existing
node in the system. After that you can go back and make the setting consistent across the
cluster.

-ryan

On Tue, Dec 7, 2010 at 7:01 AM, Nick Bailey <nick@riptano.com> wrote:
Yes, cassandra only reads the configuration when it starts up. However seed nodes are only
used when a node starts. After that they aren't needed. There should be no reason to restart
your cluster after adding a seed node to  your cluster.



On Tue, Dec 7, 2010 at 2:09 AM, aaron morton <aaron@thelastpickle.com> wrote:
You will need to restart the nodes for them to pickup changes in cassandra.yaml


Aaron


On 7 Dec 2010, at 16:32, lei liu wrote:

Thanks Nick.

After I add the new node as seed node in the configuration for all of my nodes, do I need
to restart all of my nodes?

2010/12/7 Nick Bailey <nick@riptano.com>
The node can be set as a seed node at any time. It does not need to be a seed node when it
joins the cluster. You should remove it as a seed node, set autobootstrap to true and let
it join the cluster. Once it has joined the cluster you should add it as a seed node in the
configuration for all of your nodes.



On Mon, Dec 6, 2010 at 9:59 AM, lei liu <liulei412@gmail.com> wrote:
Thank Jonathan for your reply.

How  can I bootstrap the node into cluster, I know if the node is seed node, I can't set
AutoBootstrap to true.

2010/12/6 Jonathan Ellis <jbellis@gmail.com>
set it as a seed _after_ bootstrapping it into the cluster.


On Mon, Dec 6, 2010 at t5:01 AM, lei liu <liulei412@gmail.com> wrote:
> After one seed node crash, I want to add one node as seed node, I set
> auto_bootstrap to true, but the new node don't migrate data from other
> node s.
>
> How can I add one new seed node and let the node to migrate data from other
> nodes?
>
>
>
> Thanks,
>
> LiuLei
>



--
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com









-- 

Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com



-- 
Eric Gilmore
Consulting Technical Writer
Riptano, Inc.
Ph: 510 684 9786  (cell)




-- 

Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com


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