Using ZooKeeper from Scratch
ZooKeeper is an open-source, highly reliable, and distributed consistency coordination service. ZooKeeper is designed to solve the problem that data consistency cannot be ensured for complex and error-prone distributed systems. There is no need to develop dedicated collaborative applications, which is suitable for high availability services to ensure data consistency.
Background Information
Before using the client, you need to download and update the client configuration file on all clients except the client of the active management node.
Procedure
For MRS 2.x or earlier, perform the following operations:
- Download the client configuration file.
- Log in to the MRS console. In the left navigation pane, choose , and click the cluster to be operated.
- Click the Components tab.
- Log in to the active management node of MRS Manager.
- On the MRS console, choose Clusters > Active Clusters and click a cluster name. On the Nodes tab, view the node names. The node whose name contains master1 is the Master1 node, and the node whose name contains master2 is the Master2 node.
The active and standby management nodes of MRS Manager are installed on Master nodes by default. Because Master1 and Master2 are switched over in active and standby mode, Master1 is not always the active management node of MRS Manager. Run a command in Master1 to check whether Master1 is active management node of MRS Manager. For details about the command, see 2.d.
- Log in to the Master1 node using the password as user root.
- Run the following commands to switch to user omm:
sudo su - root
su - omm
- Run the following command to check the active management node of MRS Manager:
sh ${BIGDATA_HOME}/om-0.0.1/sbin/status-oms.sh
In the command output, the node whose HAActive is active is the active management node, and the node whose HAActive is standby is the standby management node. In the following example, mgtomsdat-sh-3-01-1 is the active management node, and mgtomsdat-sh-3-01-2 is the standby management node.
Ha mode double NodeName HostName HAVersion StartTime HAActive HAAllResOK HARunPhase 192-168-0-30 mgtomsdat-sh-3-01-1 V100R001C01 2014-11-18 23:43:02 active normal Actived 192-168-0-24 mgtomsdat-sh-3-01-2 V100R001C01 2014-11-21 07:14:02 standby normal Deactived
- Log in to the active management node, for example, 192-168-0-30 of MRS Manager as user root, and run the following command to switch to user omm:
sudo su - omm
- On the MRS console, choose Clusters > Active Clusters and click a cluster name. On the Nodes tab, view the node names. The node whose name contains master1 is the Master1 node, and the node whose name contains master2 is the Master2 node.
- Run the following command to switch to the client installation directory, for example, /opt/client:
cd /opt/client
- Run the following command to update the client configuration for the active management node.
sh refreshConfig.sh /opt/client Full path of the client configuration file package
For example, run the following command:
sh refreshConfig.sh /opt/client/tmp/MRS-client/MRS_Services_Client.tar
If the following information is displayed, the configurations have been updated successfully:
ReFresh components client config is complete. Succeed to refresh components client config.
You can also refer to method 2 in Updating a Client (Versions Earlier Than 3.x) to perform operations in 1 to 4.
- Use the client on a Master node.
- On the active management node where the client is updated, for example, node 192-168-0-30, run the following command to go to the client directory:
cd /opt/client
- Run the following command to configure environment variables:
- If Kerberos authentication is enabled for the current cluster, run the following command to authenticate the current user. If Kerberos authentication is disabled for the current cluster, skip this step:
Example: kinit zookeeperuser.
- Run the following Zookeeper client command:
zkCli.sh -server <zookeeper installation node IP>:<port>
Example: zkCli.sh -server node-master1DGhZ:2181
- On the active management node where the client is updated, for example, node 192-168-0-30, run the following command to go to the client directory:
- Run the ZooKeeper client command.
- Create a ZNode.
create /test
- View ZNode information.
ls /
- Write data to the ZNode.
set /test "zookeeper test"
- View the data written to the ZNode.
get /test
- Delete the created ZNode.
delete /test
- Create a ZNode.
For MRS 3.x or later, perform the following operations:
- Download the client configuration file.
- Log in to FusionInsight Manager. For details, see Accessing FusionInsight Manager (MRS 3.x or Later).
- Choose Cluster > Name of the desired cluster > Dashboard > More > Download Client.
- Download the cluster client.
Set Select Client Type to Configuration Files Only, select a platform type, and click OK to generate the client configuration file which is then saved in the /tmp/FusionInsight-Client/ directory on the active management node by default.
- Log in to the active management node of Manager.
- Log in to any node where Manager is deployed as user root.
- Run the following command to identify the active and standby nodes:
sh ${BIGDATA_HOME}/om-server/om/sbin/status-oms.sh
In the command output, the value of HAActive for the active management node is active, and that for the standby management node is standby. In the following example, node-master1 is the active management node, and node-master2 is the standby management node.
HAMode double NodeName HostName HAVersion StartTime HAActive HAAllResOK HARunPhase 192-168-0-30 node-master1 V100R001C01 2020-05-01 23:43:02 active normal Actived 192-168-0-24 node-master2 V100R001C01 2020-05-01 07:14:02 standby normal Deactived
- Log in to the primary management node as user root and run the following command to switch to user omm:
sudo su - omm
- Run the following command to switch to the client installation directory, for example, /opt/client:
cd /opt/client
- Run the following command to update the client configuration for the active management node.
sh refreshConfig.sh /opt/client Full path of the client configuration file package
For example, run the following command:
sh refreshConfig.sh /opt/client /tmp/FusionInsight-Client/FusionInsight_Cluster_1_Services_Client.tar
If the following information is displayed, the configurations have been updated successfully:
ReFresh components client config is complete. Succeed to refresh components client config.
- Use the client on a Master node.
- On the active management node where the client is updated, for example, node 192-168-0-30, run the following command to go to the client directory:
cd /opt/client
- Run the following command to configure environment variables:
- If Kerberos authentication has been enabled for the current cluster, run the following command to authenticate the current user.. If Kerberos authentication is disabled for the current cluster, skip this step:
Example: kinit zookeeperuser.
- Run the following Zookeeper client command:
zkCli.sh -server <zookeeper installation node IP>:<port>
Example: zkCli.sh -server node-master1DGhZ:2181
- On the active management node where the client is updated, for example, node 192-168-0-30, run the following command to go to the client directory:
- Run the ZooKeeper client command.
- Create a ZNode.
create /test
- View ZNode information.
ls /
- Write data to the ZNode.
set /test "zookeeper test"
- View the data written to the ZNode.
get /test
- Delete the created ZNode.
delete /test
- Create a ZNode.
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