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 relativeľ 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