Cluster Administration Commands

This document explains usage of the riak-admin cluster interface, which enables you to perform a wide variety of cluster-level actions.

How Cluster Administration Works

Riak provides a multi-phased approach to cluster administration that enables you to stage and review cluster-level changes prior to committing them. This allows you to group multiple changes together, such as adding multiple nodes at once, adding some nodes and removing others, etc.

Enacting cluster-level changes typically follows this set of steps:

Choose an action or set of actions, such as adding a node, removing multiple nodes, etc. These actions will be staged rather than executed immediately.
Plan the changes using the cluster plan command. This will return a list of staged commands that you can review.
Commit the changes using the cluster commit command. This will execute the changes that have been staged and reviewed.

Note on command names

Many of the commands available through the riak-admin cluster interface are also available as self-standing commands. The riak-admin member-status command is now the riak-admin cluster status command, riak-admin join is now riak-admin cluster join, etc.

We recommend using the riak-admin cluster interface over the older, deprecated commands. You will receive a deprecation warning if you use the older commands.

status

Displays a variety of information about the cluster.

riak-admin cluster status

This will return output like the following in a 3-node cluster:

---- Cluster Status ----
Ring ready: true

+--------------------+------+-------+-----+-------+
|        node        |status| avail |ring |pending|
+--------------------+------+-------+-----+-------+
| (C) dev1@127.0.0.1 |valid |  up   | 34.4|  --   |
|     dev2@127.0.0.1 |valid |  up   | 32.8|  --   |
|     dev3@127.0.0.1 |valid |  up   | 32.8|  --   |
+--------------------+------+-------+-----+-------+

In the above output, Ring ready denotes whether or not the cluster agrees on the ring, i.e. whether the cluster is ready to begin taking requests.

The following information is then displayed for each node, by nodename (in this case dev1@127.0.0.1, etc.):

status - There are five possible values for status:
- valid - The node has begun participating in cluster operations
- leaving - The node is is currently unloading ownership of its data partitions to other nodes
- exiting - The node’s ownership transfers are complete and it is currently shutting down
- joining - The node is in the process of joining the cluster but but has not yet completed the join process
- down - The node is not currently responding
avail - There are two possible values: up if the node is available and taking requests and down! if the node is unavailable
ring - What percentage of the Riak ring the node is responsible for
pending - The number of pending transfers to or from the node

In addition, the cluster’s claimant node node will have a (C) next to it.

join

Joins the current node to another node in the cluster.

riak-admin cluster join <node>

You must specify a node to join to by nodename. You can join to any node in the cluster. The following would join the current node to riak1@127.0.0.1:

riak-admin cluster join riak1@127.0.0.1

Once a node joins, all of the operations necessary to establish communication with all other nodes proceeds automatically.

Note: As with all cluster-level actions, the changes made when you run the cluster join command will take effect only after you have both planned the changes by running riak-admin cluster plan and committed the changes by running riak-admin cluster commit. You can stage multiple joins before planning/committing.

leave

Instructs the current node to hand off its data partitions, leave the cluster, and shut down.

riak-admin cluster leave

You can also instruct another node (by nodename) to leave the cluster:

riak-admin cluster leave <node>

Note: As with all cluster-level actions, the changes made when you run the cluster leave command will take effect only after you have both planned the changes by running riak-admin cluster plan and committed the changes by running riak-admin cluster commit. You can stage multiple leave command before planning/committing.

force-remove

Removes another node from the cluster (by nodename) without first handing off its data partitions. This command is designed for crashed, unrecoverable nodes and should be used with caution.

riak-admin cluster force-remove <node>

Note: As with all cluster-level actions, the changes made when you run the cluster force-remove command will take effect only after you have both planned the changes by running riak-admin cluster plan and committed the changes by running riak-admin cluster commit. You can stage multiple force-remove actions before planning/committing.

replace

Instructs a node to transfer all of its data partitions to another node and then to leave the cluster and shut down.

riak-admin cluster replace <node1> <node2>

Note: As with all cluster-level actions, the changes made when you run the cluster replace command will take effect only after you have both planned the changes by running riak-admin cluster plan and committed the changes by running riak-admin cluster commit. You can stage multiple replace actions before planning/committing.

force-replace

Reassigns all data partitions owned by one node to another node without first handing off data.

riak-admin force-replace <node_being_replaced> <replacement_node>

Once the data partitions have been reassigned, the node that is being replaced will be removed from the cluster.

Note: As with all cluster-level actions, the changes made when you run the cluster force-replace command will take effect only after you have both planned the changes by running riak-admin cluster plan and committed the changes by running riak-admin cluster commit. You can stage multiple force-replace actions before planning/committing.

plan

Displays the currently staged cluster changes.

riak-admin cluster plan

riak-admin cluster plan is complex, depending on the staged changes.

If a leave operation has been staged, riak-admin cluster plan will undo the staged change and no node will be stopped.
If a join operation has been staged, the joining node will be shut down after its ring has been cleared. When this node restarts, it will behave like a fresh unjoined node and can be joined again.
If a cluster clear operation is staged on a node that remains in the cluster, running riak-admin cluster plan will leave the node unaffected.

If there is no current cluster plan, the output will be There are no staged changes.

If there is a staged change (or changes), however, you will see a detailed listing of what will take place upon commit, what the cluster will look like afterward, etc.

For example, if a cluster leave operation is staged in a 3-node cluster the output will look something like this:

=============================== Staged Changes ================================
Action         Details(s)
-------------------------------------------------------------------------------
leave          'dev2@127.0.0.1'
-------------------------------------------------------------------------------

NOTE: Applying these changes will result in 2 cluster transitions

###############################################################################
                         After cluster transition 1/2
###############################################################################

================================= Membership ==================================
Status     Ring    Pending    Node
-------------------------------------------------------------------------------
leaving    32.8%      0.0%    'dev2@127.0.0.1'
valid      34.4%     50.0%    'dev1@127.0.0.1'
valid      32.8%     50.0%    'dev3@127.0.0.1'
-------------------------------------------------------------------------------
Valid:2 / Leaving:1 / Exiting:0 / Joining:0 / Down:0

WARNING: Not all replicas will be on distinct nodes

Transfers resulting from cluster changes: 38
  6 transfers from 'dev1@127.0.0.1' to 'dev3@127.0.0.1'
  11 transfers from 'dev3@127.0.0.1' to 'dev1@127.0.0.1'
  5 transfers from 'dev2@127.0.0.1' to 'dev1@127.0.0.1'
  16 transfers from 'dev2@127.0.0.1' to 'dev3@127.0.0.1'

###############################################################################
                        After cluster transition 2/2
###############################################################################

================================= Membership ==================================
Status     Ring    Pending    Node
-------------------------------------------------------------------------------
valid      50.0%      --      'dev1@127.0.0.1'
valid      50.0%      --      'dev3@127.0.0.1'
-------------------------------------------------------------------------------
Valid:2 / Leaving:0 / Exiting:0 / Joining:0 / Down:0

WARNING: Not all replicas will be on distinct nodes

Notice that there are distinct sections of the output for each of the transitions that the cluster will undergo, including warnings, planned data transfers, etc.

commit

Commits the currently staged cluster changes. Staged cluster changes must be reviewed using riak-admin cluster plan prior to being committed.

riak-admin cluster commit

clear

Clears the currently staged cluster changes.

riak-admin cluster clear

partitions

Prints primary, secondary, and stopped partition indices and IDs either for the current node or for another, specified node. The following prints that information for the current node:

riak-admin cluster partitions

This would print the partition information for a different node in the cluster:

riak-admin cluster partitions --node=<node>

Partition information is contained in a table like this:

Partitions owned by 'dev1@127.0.0.1':
+---------+-------------------------------------------------+--+
|  type   |                      index                      |id|
+---------+-------------------------------------------------+--+
| primary |                        0                        |0 |
| primary | 91343852333181432387730302044767688728495783936 |4 |
| primary |182687704666362864775460604089535377456991567872 |8 |
|   ...   |                      ....                       |..|
| primary |1438665674247607560106752257205091097473808596992|63|
|secondary|                       --                        |--|
| stopped |                       --                        |--|
+---------+-------------------------------------------------+--+

partition-count

Displays the current partition count either for the whole cluster or for a particular node. This would display the partition count for the cluster:

riak-admin cluster partition-count

This would display the count for a node:

riak-admin cluster partition-count --node=<node>

When retrieving the partition count for a node, you’ll see a table like this:

+--------------+----------+-----+
|     node     |partitions| pct |
+--------------+----------+-----+
|dev1@127.0.0.1|    22    | 34.4|
+--------------+----------+-----+

The partitions column displays the number of partitions claimed by the node, while the pct column displays the percentage of the ring claimed.

partition

The cluster partition command enables you to convert partition IDs to indexes and vice versa using the partition id and partition index commands, respectively. Let’s say that you run the riak-admin cluster partitions command and see that you have a variety of partitions, one of which has an index of 1004782375664995756265033323.0.844576013453623296. You can convert that index to an ID like this:

riak-admin cluster partition index=1004782375664995756265033323.0.844576013453623296

Conversely, if you have a partition with an ID of 20, you can retrieve the corresponding index:

riak-admin cluster partition id=20