Joining cluster without claiming partition

[ukazap]

Hi, suppose I have 4 nodes and want to divvy up the v-nodes among node1..node3.

# before node4 joining
iex([email protected])16> :riak_core_console.member_status([])
================================= Membership ==================================
Status     Ring    Pending    Node
-------------------------------------------------------------------------------
valid      37.5%      --      '[email protected]'
valid      31.3%      --      '[email protected]'
valid      31.3%      --      '[email protected]'
-------------------------------------------------------------------------------
Valid:3 / Leaving:0 / Exiting:0 / Joining:0 / Down:0

What would it take to make node4 "passive" (does not claim partition/start v-nodes)?

Here's what I've tried: skipping :riak_core.register/1 and :riak_core_node_watcher.service_up/2 in node4 startup, but when I connected node4 into the cluster and start the claimant process (:riak_core_claimant.plan/0 and :riak_core_claimant.commit/0), although sent commands are still successfully routed (to vnodes in node1, node2, and node3), all the nodes are stuck in pending trying to rebalance (?).

iex([email protected])13> :riak_core_console.member_status([])
================================= Membership ==================================
Status     Ring    Pending    Node
-------------------------------------------------------------------------------
valid      37.5%     25.0%    '[email protected]'
valid      31.3%     25.0%    '[email protected]'
valid      31.3%     25.0%    '[email protected]'
valid       0.0%     25.0%    '[email protected]'
-------------------------------------------------------------------------------
Valid:4 / Leaving:0 / Exiting:0 / Joining:0 / Down:0
:ok
iex([email protected])14> {:ok, ring} = :riak_core_ring_manager.get_my_ring()
iex([email protected])15> :riak_core_ring.pretty_print(ring, [:legend])
==================================== Nodes ====================================
Node a: 6 ( 37.5%) [email protected]
Node b: 5 ( 31.3%) [email protected]
Node c: 5 ( 31.3%) [email protected]
Node d: 0 (  0.0%) [email protected]
==================================== Ring =====================================
abca|abcb|abcc|abca|
:ok

[albsch]

I don't think joining a cluster without intended participation is supported. What is a passive node supposed to do after joining?

[ukazap]

The passive node will act as a client that is able to send commands to one or more of the vnodes in the cluster.

Or is there a more established way to achieve that?

[albsch]

I get what you mean now. Sadly, this is not supported by riak_core, your case is a special case of assigning workload to different loads, where your assigned workload of that passive node would be 0.

See issue #40 :

Server capacity adjustment by “weighting” did not exist: all servers were assumed equal.

I don't know when and how this issue will be tackled, as the project is currently only in maintenance mode. If someone is up to the task and tries to implement it, it would be a welcomed contribution.

Going to close this issue, as this is tracked in the other bigger issue.