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The "FAQ_JP" page has been changed by MakiWatanabe. The comment on this change is: Add #seed and #seed_spof. http://wiki.apache.org/cassandra/FAQ_JP?action=diff&rev1=82&rev2=83 -------------------------------------------------- * [[#replicaplacement|Cassandraはどのデータがどのノードに配置されているかをどのように判定しますか？]] * [[#cachehitrateunits|JMXで行キャッシュあるいはキーキャッシュのヒット率が0.XX123456789のように表示されます。これはXX%という意味でしょうか？それとも0.XX%でしょうか？]] * [[#bigcommitlog|Commit Logが大変肥大化しています。Cassandraは古いCommit Logを削除しないのでしょうか？]] + * [[#seed|What are seeds?]] + * [[#seed_spof|Does single seed mean single point of failure?]] + <<Anchor(cant_listen_on_ip_any)>> @@ -499, +502 @@ update column family XXX with memtable_flush_after=60; + <<Anchor(seed)>> + + + == What are seeds? == + + If you configure your nodes to refer some node as seed, nodes in your ring tend to send Gossip message to seeds more often ( Refer to [[ArchitectureGossip]] for 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. + + Seeds are also referred by new nodes on bootstrap to learn other nodes in ring. + 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. + + + <<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. +
