普段の挙動
Riakにデータがコミットされると、どのvnodeに格納するかが計算されて、そのあとに実行される。
複数台構成を前提として、Riakの前にLBを置いてアクセスを分散させている場合、どのノードにいつデータがコミットされるか分からない状態だ。
該当のデータを持っていない（持つべきでない）ノードは、持っているノードに問い合わせることで処理を実行する。
riak-admin cluster leave
今回は、devrelで作成した開発環境でleaveコマンドを試してみる。
本当は物理4台でriakクラスタを構成し、LANケーブルをハサミで切って確かめたかったが、時間もお金もなかったので…
➜ riak git:(a12d5a2) dev/dev1/bin/riak-admin member-status
================================= Membership ==================================
Status Ring Pending Node
-------------------------------------------------------------------------------
valid 25.0% -- 'dev1@127.0.0.1'
valid 25.0% -- 'dev3@127.0.0.1'
valid 25.0% -- 'dev4@127.0.0.1'
valid 25.0% -- 'dev5@127.0.0.1'
-------------------------------------------------------------------------------
Valid:4 / Leaving:0 / Exiting:0 / Joining:0 / Down:0
このような4台のクラスタだとする。
で、dev4を操作し、クラスタから離脱させる。
➜ riak git:(a12d5a2) dev/dev4/bin/riak-admin cluster leave
Success: staged leave request for 'dev4@127.0.0.1'
###############################################################################
After cluster transition 1/2
###############################################################################
================================= Membership ==================================
Status Ring Pending Node
-------------------------------------------------------------------------------
leaving 25.0% 0.0% 'dev4@127.0.0.1'
valid 25.0% 34.4% 'dev1@127.0.0.1'
valid 25.0% 32.8% 'dev3@127.0.0.1'
valid 25.0% 32.8% 'dev5@127.0.0.1'
-------------------------------------------------------------------------------
Valid:3 / Leaving:1 / Exiting:0 / Joining:0 / Down:0
###############################################################################
After cluster transition 2/2
###############################################################################
================================= Membership ==================================
Status Ring Pending Node
-------------------------------------------------------------------------------
valid 34.4% -- 'dev1@127.0.0.1'
valid 32.8% -- 'dev3@127.0.0.1'
valid 32.8% -- 'dev5@127.0.0.1'
-------------------------------------------------------------------------------
Valid:3 / Leaving:0 / Exiting:0 / Joining:0 / Down:0
そして変更をコミットさせると、データが移動していくのがわかる。
大体1分くらいで、移動が完了する。
➜ riak git:(a12d5a2) dev/dev1/bin/riak-admin cluster commit
Cluster changes committed
➜ riak git:(a12d5a2) dev/dev1/bin/riak-admin member-status
================================= Membership ==================================
Status Ring Pending Node
-------------------------------------------------------------------------------
valid 25.0% -- 'dev1@127.0.0.1'
valid 25.0% -- 'dev3@127.0.0.1'
valid 25.0% -- 'dev4@127.0.0.1'
valid 25.0% -- 'dev5@127.0.0.1'
-------------------------------------------------------------------------------
Valid:4 / Leaving:0 / Exiting:0 / Joining:0 / Down:0
➜ riak git:(a12d5a2) dev/dev1/bin/riak-admin cluster commit
Cluster changes committed
➜ riak git:(a12d5a2) dev/dev1/bin/riak-admin member-status
================================= Membership ==================================
Status Ring Pending Node
-------------------------------------------------------------------------------
leaving 21.9% 0.0% 'dev4@127.0.0.1'
valid 23.4% 34.4% 'dev1@127.0.0.1'
valid 25.0% 32.8% 'dev3@127.0.0.1'
valid 29.7% 32.8% 'dev5@127.0.0.1'
-------------------------------------------------------------------------------
Valid:3 / Leaving:1 / Exiting:0 / Joining:0 / Down:0
➜ riak git:(a12d5a2) dev/dev1/bin/riak-admin member-status
================================= Membership ==================================
Status Ring Pending Node
-------------------------------------------------------------------------------
leaving 14.1% 0.0% 'dev4@127.0.0.1'
valid 25.0% 34.4% 'dev1@127.0.0.1'
valid 28.1% 32.8% 'dev3@127.0.0.1'
valid 32.8% 32.8% 'dev5@127.0.0.1'
-------------------------------------------------------------------------------
Valid:3 / Leaving:1 / Exiting:0 / Joining:0 / Down:0
➜ riak git:(a12d5a2) dev/dev1/bin/riak-admin member-status
================================= Membership ==================================
Status Ring Pending Node
-------------------------------------------------------------------------------
leaving 9.4% 0.0% 'dev4@127.0.0.1'
valid 28.1% 34.4% 'dev1@127.0.0.1'
valid 29.7% 32.8% 'dev3@127.0.0.1'
valid 32.8% 32.8% 'dev5@127.0.0.1'
-------------------------------------------------------------------------------
Valid:3 / Leaving:1 / Exiting:0 / Joining:0 / Down:0
➜ riak git:(a12d5a2) dev/dev1/bin/riak-admin member-status
================================= Membership ==================================
Status Ring Pending Node
-------------------------------------------------------------------------------
leaving 0.0% -- 'dev4@127.0.0.1'
valid 34.4% -- 'dev1@127.0.0.1'
valid 32.8% -- 'dev3@127.0.0.1'
valid 32.8% -- 'dev5@127.0.0.1'
-------------------------------------------------------------------------------
Valid:3 / Leaving:1 / Exiting:0 / Joining:0 / Down:0
このように、Leaveコマンドを使った場合は段階的にそのノードが持っているデータが他のクラスタに移されることがわかる。
追加したとき
追加するノードが動いていることを確認したら、クラスタにplanで確認してcommitsする。
➜ riak git:(a12d5a2) dev/dev4/bin/riak-admin cluster join dev1@127.0.0.1
Success: staged join request for 'dev4@127.0.0.1' to 'dev1@127.0.0.1'
➜ riak git:(a12d5a2) dev/dev1/bin/riak-admin cluster plan
=============================== Staged Changes ================================
Action Details(s)
-------------------------------------------------------------------------------
join 'dev4@127.0.0.1'
-------------------------------------------------------------------------------
NOTE: Applying these changes will result in 1 cluster transition
###############################################################################
After cluster transition 1/1
###############################################################################
================================= Membership ==================================
Status Ring Pending Node
-------------------------------------------------------------------------------
valid 34.4% 25.0% 'dev1@127.0.0.1'
valid 32.8% 25.0% 'dev3@127.0.0.1'
valid 0.0% 25.0% 'dev4@127.0.0.1'
valid 32.8% 25.0% 'dev5@127.0.0.1'
-------------------------------------------------------------------------------
Valid:4 / Leaving:0 / Exiting:0 / Joining:0 / Down:0
Transfers resulting from cluster changes: 47
5 transfers from 'dev3@127.0.0.1' to 'dev4@127.0.0.1'
5 transfers from 'dev1@127.0.0.1' to 'dev3@127.0.0.1'
5 transfers from 'dev5@127.0.0.1' to 'dev1@127.0.0.1'
5 transfers from 'dev3@127.0.0.1' to 'dev5@127.0.0.1'
5 transfers from 'dev1@127.0.0.1' to 'dev4@127.0.0.1'
5 transfers from 'dev5@127.0.0.1' to 'dev3@127.0.0.1'
5 transfers from 'dev3@127.0.0.1' to 'dev1@127.0.0.1'
6 transfers from 'dev1@127.0.0.1' to 'dev5@127.0.0.1'
6 transfers from 'dev5@127.0.0.1' to 'dev4@127.0.0.1'
➜ riak git:(a12d5a2) dev/dev1/bin/riak-admin cluster commit
Cluster changes committed
➜ riak git:(a12d5a2) dev/dev1/bin/riak-admin member-status
================================= Membership ==================================
Status Ring Pending Node
-------------------------------------------------------------------------------
valid 34.4% 25.0% 'dev1@127.0.0.1'
valid 32.8% 25.0% 'dev3@127.0.0.1'
valid 0.0% 25.0% 'dev4@127.0.0.1'
valid 32.8% 25.0% 'dev5@127.0.0.1'
-------------------------------------------------------------------------------
Valid:4 / Leaving:0 / Exiting:0 / Joining:0 / Down:0
あとは先ほどと同様の挙動を示す。
➜ riak git:(a12d5a2) dev/dev1/bin/riak-admin cluster commit
Cluster changes committed
➜ riak git:(a12d5a2) dev/dev1/bin/riak-admin member-status
================================= Membership ==================================
Status Ring Pending Node
-------------------------------------------------------------------------------
valid 34.4% 25.0% 'dev1@127.0.0.1'
valid 32.8% 25.0% 'dev3@127.0.0.1'
valid 0.0% 25.0% 'dev4@127.0.0.1'
valid 32.8% 25.0% 'dev5@127.0.0.1'
-------------------------------------------------------------------------------
Valid:4 / Leaving:0 / Exiting:0 / Joining:0 / Down:0
➜ riak git:(a12d5a2) dev/dev1/bin/riak-admin member-status
================================= Membership ==================================
Status Ring Pending Node
-------------------------------------------------------------------------------
valid 31.3% 25.0% 'dev1@127.0.0.1'
valid 32.8% 25.0% 'dev3@127.0.0.1'
valid 3.1% 25.0% 'dev4@127.0.0.1'
valid 32.8% 25.0% 'dev5@127.0.0.1'
-------------------------------------------------------------------------------
Valid:4 / Leaving:0 / Exiting:0 / Joining:0 / Down:0
➜ riak git:(a12d5a2) dev/dev1/bin/riak-admin member-status
================================= Membership ==================================
Status Ring Pending Node
-------------------------------------------------------------------------------
valid 25.0% -- 'dev1@127.0.0.1'
valid 25.0% -- 'dev3@127.0.0.1'
valid 25.0% -- 'dev4@127.0.0.1'
valid 25.0% -- 'dev5@127.0.0.1'
-------------------------------------------------------------------------------
Valid:4 / Leaving:0 / Exiting:0 / Joining:0 / Down:0