Dear Wiki user, You have subscribed to a wiki page or wiki category on "Cassandra Wiki" for change notification.
The "FAQ" page has been changed by MakiWatanabe. The comment on this change is: Add #seed and #seed_spof. http://wiki.apache.org/cassandra/FAQ?action=diff&rev1=114&rev2=115 -------------------------------------------------- * [[#replicaplacement|How does Cassandra decide which nodes have what data?]] * [[#cachehitrateunits|I have a row or key cache hit rate of 0.XX123456789. Is that XX% or 0.XX% ?]] * [[#bigcommitlog|Commit Log gets very big. Cassandra does not delete "old" commit logs. Why?]] + * [[#seed|What are seeds?]] + * [[#seed_spof|Does single seed mean single point of failure?]] + <<Anchor(cant_listen_on_ip_any)>> @@ -431, +434 @@ update column family XXX with memtable_flush_after=60; + <<Anchor(seed)>> + + == 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 ( Refer to [[ArchitectureGossip]] for more + details ) than to non-seeds. In other words, seeds are worked as hubs of Gossip network. + With seeds, each node can detect status changes of other nodes quickly. + + <<Anchor(seed_spof)>> + + == 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. However, it will need more time to spread status changes of node over the ring. + It is recommended to have multiple seeds in production system. +
