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From Apache Wiki <>
Subject [Cassandra Wiki] Update of "Operations_JP" by MakiWatanabe
Date Fri, 18 Feb 2011 07:24:58 GMT
Dear Wiki user,

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The "Operations_JP" page has been changed by MakiWatanabe.


- == Moving or Removing nodes ==
- === Removing nodes entirely ===
- You can take a node out of the cluster with `nodetool decommission` to a live node, or `nodetool
removetoken` (to any other machine) to remove a dead one.  This will assign the ranges the
old node was responsible for to other nodes, and replicate the appropriate data there. If
`decommission` is used, the data will stream from the decommissioned node. If `removetoken`
is used, the data will stream from the remaining replicas.
+ == ノードの移動と削除 ==
+ === ノードの削除 ===
+ 稼働中のノードをクラスタから取り除くには`nodetool decommission`を実行します。停止中のノードをクラスタから取り除くには稼働中のノードで`nodetool
- No data is removed automatically from the node being decommissioned, so if you want to put
the node back into service at a different token on the ring, it should be removed manually.
+ データはdecomissionされるノードから自動削除されません。もしそのノードを別のトークンを指定してクラスタに再接続する場合は、あらかじめ手動でデータを削除して下さい。
- === Moving nodes ===
- `nodetool move`: move the target node to a given Token. Moving is essentially a convenience
over decommission + bootstrap.
+ === ノードの移動 ===
+ `nodetool move`: ノードを指定したトークンに移動します。この操作は基本的にはdecommissionとbootstrapを組み合わせたものです。
- As with bootstrap, see [[Streaming]] for how to monitor progress.
+ ブートストラップの進捗確認については, [[Streaming]]を参照して下さい。
- === Load balancing ===
- If you add nodes to your cluster your ring will be unbalanced and only way to get perfect
balance is to compute new tokens for every node and assign them to each node manually by using
nodetool move command.
+ === 負荷分散 ===
+ 単純にノードを追加した場合、クラスタリングのデータ格納バランスは不均等になるでしょう。これを調整して均等な格納バランスを得るためには、すべてのノードのトークンを計算し直し、`nodetool
- Here's a python program which can be used to calculate new tokens for the nodes. There's
more info on the subject at Ben Black's presentation at Cassandra Summit 2010.
+ 以下にトークンを再計算するためのpythonプログラムを示します。この話題についてはCassandra
Summit 2010におけるBen Blackによるプレゼンテーションでさらに詳しく説明されています。
    def tokens(nodes):                        
        for x in xrange(nodes):         
            print 2 ** 127 / nodes * x
- There's also `nodetool loadbalance`: essentially a convenience over decommission + bootstrap,
only instead of telling the target node where to move on the ring it will choose its location
based on the same heuristic as Token selection on bootstrap. You should not use this as it
doesn't rebalance the entire ring.
+ `nodetool loadbalance`は指定ノードに対してトークン選択の項で説明した自動トークン選択ルールに基づいて新たなトークンを決定し、decomissionとbootstrapを実行するコマンドです。このコマンドではリング全体の負荷均等化は行えません。
- The status of move and balancing operations can be monitored using `nodetool` with the `streams`
+ 移動やデータ格納量の均等化状況は`nodetool`に`streams`引数を与えることで監視できます。
  == Consistency ==
  Cassandra allows clients to specify the desired consistency level on reads and writes. 
(See [[API]].)  If R + W > N, where R, W, and N are respectively the read replica count,
the write replica count, and the replication factor, all client reads will see the most recent
write.  Otherwise, readers '''may''' see older versions, for periods of typically a few ms;
this is called "eventual consistency."  See
and for more.

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