setting-autoreprovision

setting-autoreprovision

Modifies auto-reprovision settings

SYNTAX

couchbase-cli setting-autoreprovision [--cluster <url>] [--username <user>] [--password <password>] [--enabled <1|0>] [--max-nodes <num>]

DESCRIPTION

Auto-reprovisioning is used in order to prevent dataloss in ephemeral buckets during failure scenarios when a node crashes and restarts quickly. Under this scenario auto-reprovisioning ensures that an ephemeral bucket’s replica vbuckets are prmoted to active state. This mechanism is not needed for Couchbase buckets because a Couchbase buckets data is persisted to disk and can be loaded back into memory after a node restarts. Ephemeral buckets on the other hand completely lose their data when a node crashes and replicas must be relied upon in order to prevent dataloss. If ephemeral buckets are not in use this setting has no effect on the cluster.

Auto-reprovisioning can either be enabled or disabled. If you have ephemeral buckets it is always recommended that auto-reprovisioning is enabled otherwise the cluster will experience dataloss if a node crashes or is restarted. Users can also specify the number of nodes that can be auto-reprovisioned before the cluster is rebalanced. An auto-reprovision event occurs if a cluster has at least one ephemeral bucket and a node crashes and restarts. If the number of crashes and restarts exceed the maximum number of nodes that can be auto-reprovisioned then the next crash and restart will result in dataloss for all ephemeral buckets in the cluster.

When setting the max nodes parameter, note that specifying the max nodes to be too high could result in cascading node failures. This can happen because when a node fails and restarts the server load for the crashed node is distributed to the rest of the servers in the cluster. This extra load could cause the one or more of the remaining servers in the cluster to become overloaded and unresponsive leading to more failures. On the other hand specifying max nodes to be too small could lead to dataloss if there are many failures in the cluster at the same time. How this variable is set depends on the cluster size, workload, and configuration. However, it is always recommended that auto-reprovisioning is at least enabled and that max nodes is set to at least 1.

OPTIONS

-c
--cluster

Specfies the hostname of a node in the cluster. See the HOST FORMATS section for more information on specifying a hostname.

-u
--user <username>

Specifies the username of the user executing the command. If you do not have a user account with permision to execute the command then it will fail with an unauthorized error.

-p
--password <password>

Specifies the password of the user executing the command. If you do not have a user account with permision to execute the command then it will fail with an unauthorized error. If this argument is specified, but no password is given then the command will prompt the user for a password through non-echoed stdin. You may also specify your password by using the environment variable CB_REST_PASSWORD.

--enabled <num>

Specifies whether or not auto-reprovisioning is enabled. Set this option to "1" to enable autofailover or "0" to disable autofailover.

--max-nodes <num>

Specifies the maximum number of servers that can be auto-reprovisioned before a rebalance must take place (which resets the count). This parameter must always be set to a number greater than or equal to 1.

HOST FORMATS

When specifying a host for the couchbase-cli command the following formats are expected:

  • couchbase://<addr>

  • <addr>:<port>

  • http://<addr>:<port>

It is recommended to use the couchbase://<addr> format for standard installations. The other two formats allow an option to take a port number which is needed for non-default installations where the admin port has been set up on a port other that 8091.

EXAMPLES

To enable auto-reprovisioning and allow up to three nodes be auto-reprovisioned before a rebalance takes place run the following command.

$ couchbase-cli setting-autoreprovision -c 192.168.1.5 -u Administrator \
 -p password --enabled 1 --max-nodes 3

To disable auto-reprovisioning run the following command.

$ couchbase-cli setting-autoreprovision -c 192.168.1.5 -u Administrator \
 -p password --enabled 0

ENVIRONMENT AND CONFIGURATION VARIABLES

CB_REST_PASSWORD Specifies the password of the user executing the command. This environment variable allows you to specify a default argument for the -p/--password argument on the command line. It also allows the user to ensure that their password are not cached in their command line history.

CB_REST_PASSWORD Specifies the password of the user executing the command. This environment variable allows you to specify a default argument for the -p/--password argument on the command line.