Performing Hard Failover

reference

Hard failover can be used to take a node out of a cluster, when the node has become unresponsive.

HTTP Method and URI

POST /controller/failOver

Description

When a node has become unresponsive, and active vBuckets have thereby become unavailable for the serving of data, hard failover should be used to take the unresponsive node out of the cluster.

During hard failover, the Cluster Manager promotes replica vBuckets to active status on the remaining cluster-nodes. A revised cluster-map is then communicated to all clients. When hard failover is complete, no further attempts are made to access vBuckets on the failed-over node, but the node has not yet been fully taken out of the cluster. The cluster is at this point considered to be in a degraded state, in terms of availability; as it now contains a reduced number of replica vBuckets, and may lack resources for handling a further node-outage. Rebalance should therefore be performed.

Hard failover should not be used as part of regular, planned maintenance activities that can be conducted with all cluster-nodes available. For information, see Failover.

Curl Syntax

curl -v -X POST -u <username>:<password>
  http://<ip-address-or-hostname>:<port>/controller/failOver
  -d [otpNode=node_1@<hostname>]
  -d allowUnsafe=< true | false >

The value of each specified otpNode parameter must be the name of a node that will be hard-failed over.

The value of allowUnsafe must be either true or false (which is the default); indicating whether or not hard failover should be attempted in unsafe mode. For information, see Hard Failover in Default and Unsafe Modes.

Responses

Success returns 200 OK.

Incorrectly specifying the target cluster returns Failed to connect. Incorrectly specifying the URI returns a 404 Object Not Found error, and a Requested resource not found notification.

Specifying an unknown server to be failed over returns a 400 Bad Request notification, and an error message such as the following: Unknown server given: ["ns_1@10.143.201.106"].

Failure to authenticate returns a 401 Unauthorized notification.

Examples

The following curl statement performs a hard failover of node 10.142.180.102 from a cluster identified as 10.142.180.1.

curl -v -X POST -u Administrator:password \
http://10.142.180.1:8091/controller/failOver \
-d 'otpNode=ns_1@10.142.180.102'

The following performs a hard failover of nodes 10.142.180.102 and 10.142.180.103 from a cluster identified as 10.142.180.1. Note that multi-node failover is always hard failover.

curl -v -X POST -u Administrator:password \
http://10.142.180.1:8091/controller/failOver \
-d 'otpNode=ns_1@10.142.180.102' \
-d 'otpNode=ns_1@10.142.180.103'

The following performs an unsafe, hard failover of nodes 10.142.180.102 and 10.142.180.103 from a cluster identified as 10.142.180.1.

curl -v -X POST -u Administrator:password \
http://10.142.180.1:8091/controller/failOver \
-d otpNode=ns_1%4010.142.180.102\&otpNode=ns_1%4010.142.180.103 \
-d allowUnsafe=true