ALM-45426 ClickHouse Service Quantity Quota Usage in ZooKeeper Exceeds the Threshold

Alarm Description

The alarm module checks the quota usage of the ClickHouse service in the ZooKeeper every 60 seconds. This alarm is generated when the alarm module detects that the usage exceeds the threshold (90%).

This alarm is cleared when the system detects that the usage is lower than the threshold and the alarm is cleared.

Alarm Attributes

Alarm Parameters

Impact on the System

After the ZooKeeper quantity quota of the ClickHouse service exceeds the threshold, you cannot perform cluster operations on the ClickHouse service on FusionInsight Manager. As a result, the ClickHouse service cannot be used.

Possible Causes

• When table data is created, inserted, or deleted, the ClickHouse creates znodes on ZooKeeper nodes. As the service volume increases, the number of znodes may exceed the configured threshold.
• No quota limit is set for the metadata directory /clickhouse of ClickHouse in ZooKeeper.

Handling Procedure

Check the number of znodes created by ClickHouse on ZooKeeper.

1. Log in to the host where the ZooKeeper client is located and log in to the ZooKeeper client.

   Switch to the client installation directory.

   Example: cd /opt/client

   Run the following command to configure environment variables:

   source bigdata_env

   Run the following command to authenticate the user (skip this step in common mode):

   kinit Component service user

   Run the following command to log in to the client tool:

   zkCli.sh -server service IP address of the node where the ZooKeeper role instance locates:client port

2. Run the following command to check the quota used by the ClickHouse in the ZooKeeper and check whether the quota information is correctly set:
   listquota /clickhouse

   absolute path is /zookeeper/quota/clickhouse
   Quota for path /clickhouse does not exist.

   If the preceding information indicates that the quota configuration is incorrect, go to 3.

   If no, go to 5.

3. Log in to FusionInsight Manager and choose Cluster > Services > ZooKeeper. On the displayed page, click Configurations and click All Configurations. On this sub-tab page, search for quotas.auto.check.enable to check whether its value is true.

   If the value is not true, change the value to true and click Save.

4. On FusionInsight Manager, choose Cluster > Services > ClickHouse, click More, and select Synchronize Configuration. After the synchronization is successful, go to 1.
5. Run the following command and check whether the ratio of the count value of Output stat to the count value of Output quota in the command output is greater than 0.9:
   listquota /clickhouse

   absolute path is /zookeeper/quota/clickhouse
   Output quota for /clickhouse count=200000,bytes=1000000000
   Output stat for /clickhouse count=2667,bytes=60063

   In the preceding information, the count value of Output stat is 2667, and the count value of Output quota is 200000.

   • If yes, go to 6.
   • If no, check whether the alarm is cleared 5 minutes later. If the alarm persists, go to 8.

6. On FusionInsight Manager, choose Cluster > Services > ClickHouse. Click Configurations and then All Configurations. Search for clickhouse.zookeeper.quota.node.count, set it to a value twice the count of Output stat in 5. Do not use a value larger than 6000000. Otherwise, there will be high risks. Exercise caution when setting this parameter.
7. Restart the ClickHouse instance for which the alarm is generated, and check whether the alarm is cleared 5 minutes later.
   • If yes, no further action is required.
   • If no, perform 6 again, and check whether the alarm is cleared 5 minutes later. If the alarm persists, go to 8.

Collect the fault information.

8. On FusionInsight Manager, choose O&M. In the navigation pane on the left, choose Log > Download.
9. Expand the Service drop-down list, and select ClickHouse for the target cluster.
10. Choose the corresponding host form the host list.
11. Click the edit icon in the upper right corner, and set Start Date and End Date for log collection to 1 hour ahead of and after the alarm generation time, respectively. Then, click Download.
12. Contact O&M engineers and provide the collected logs.

Alarm Clearance

This alarm is automatically cleared after the fault is rectified.

Related Information

None.