dump zkinfo

Returns the ZooKeeper znodes.

Note: This command is used by the mapr-support-collect.sh script to gather cluster diagnostics for troubleshooting.

This command enables you to view a snapshot of the data stored in Zookeeper as a result of cluster operations

ZooKeeper prevents service coordination conflicts by enforcing a rigid set of rules and conditions, provides cluster-wide information about running services and their configuration, and provides a mechanism for almost instantaneous service failover. Warden will not start any services unless ZooKeeper is reachable and more than half of the configured ZooKeeper nodes are live.

The mapr-support-collect.sh script calls the maprcli dump supportdump command to gather cluster diagnostics for troubleshooting. For more information, see mapr-support-collect.sh.

Syntax

CLI
maprcli dump zkinfo
    [-cluster <cluster name>]
    [-zkconnect <connect string>]
Note: For best results, use the -json option from the command line.
REST
N/A

Parameters

Parameter

Description

cluster The cluster on which to run the command. If this parameter is omitted, the command is run on the same cluster where it is issued. In multi-cluster contexts, you can use this parameter to specify a different cluster on which to run the command.
zkconnect A ZooKeeper connect string, which specifies a list of the hosts running ZooKeeper, and the port to use on each, in the format: '<host>[:<port>][,<host>[:<port>]...]'. To obtain zookeeper connection strings, use the maprcli node listzookeepers command.

Output

The maprcli dump zkinfo command is run as part of support dump tools to view the current state of the Zookeeper service. The command should always be run using the -json option, since output in the default tabular format is not useful. Command output displays the data stored in the ZooKeeper hierarchical tree of znodes.

# maprcli dump zkinfo -json
{
        "timestamp":1335825202157,
        "status":"OK",
        "total":1,
        "data":[
                {
                "/_Stats":"\ncZxid = 0,ctime = Wed Dec 31 16:00:00 PST 1969,mZxid = 0,mtime = Wed Dec 31 16:00:00 PST 1969,pZxid = 516,cversion = 12,dataVersion = 0,aclVersion = 0,ephemeralOwner = 0,dataLength = 0,numChildren = 13",
                        "/":[
                                {
                                     ....
                                }
        ]
}

Output fields

You can use the maprcli dump zkinfo command as you would use a database snapshot. The /services, /services_config, /servers, and /*_locks znodes are used by Warden to store and exchange information.

Field

Description

services

The /services directory is used by Warden to store and exchange information about services.

datacenter

The /datacenter directory contains CLDB "vital signs" that you can use to identify the CLDB master, the most recent epoch, and other key data. For more information, see Moving CLDB Data.

services_config

The /services_config directory is used by Warden to store and exchange information.

zookeeper

The /zookeeper directory stores information about the ZooKeeper service.

servers

The /servers directory is used by Warden to store and exchange information.

nodes

The /nodes directory (znode) stores key information about the nodes.