Yes, two per DC is a recommendation I've heard from Jonathan Ellis. We put that in yet more documentation at http://www.datastax.com/dev/tutorials/getting_started_0.7/configuring#seed-list (appreciate the citation Aaron :)
I had a recent conversation with a Cassandra expert who had me convinced that, as long as a node online already had one seed in its list at startup, you wouldn't really need to restart it -- at least right away -- after adding a second seed to the config. Rather than confuse the issue by trying to remember/recreate the rationale for that, I'll ping him and see if he'll comment here.
AFAIK it's recommended to have two seed nodes per dc.Some info on seeds here http://www.datastax.com/docs/0.7/operations/clusteringYou will need a restart.Aaron
On 2/03/2011, at 6:08 AM, email@example.com wrote:
How many seed nodes should I have for a cluster of 100 nodes each with about 500gb of data? Also to add seeds the nodes, must I change the seed nodes list on all existing nodes through the Cassandra.yaml file? Will changes take effect without restarting the node?
Shan (Susie) Lu, Analyst
Accenture Technology Labs - Silicon Valley
cell +1 425.749.2546
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