Link to HDFS

CDM supports the following HDFS data sources:

MRS HDFS
FusionInsight HDFS
Apache HDFS

MRS HDFS

When connecting CDM to HDFS of MRS, configure the parameters as described in Table 1.

Before creating an MRS link, you need to add an authenticated Kerberos user on MRS and log in to the MRS management page to change the initial password. Then use the new user to create an MRS link.
To connect to an MRS 2.x cluster, create a CDM cluster of version 2.x first. CDM 1.8.x clusters cannot connect to MRS 2.x clusters.
If the connection fails after you select a cluster, check whether the MRS cluster can communicate with the CDM instance which functions as the agent. They can communicate with each other in the following scenarios:
- If the CDM cluster in the DataArts Studio instance and the MRS cluster are in different regions, a public network or a dedicated connection is required. If the Internet is used for communication, ensure that an EIP has been bound to the CDM cluster, and the MRS cluster can access the Internet and the port has been enabled in the firewall rule.
- If the CDM cluster in the DataArts Studio instance and the MRS cluster are in the same region, VPC, subnet, and security group, they can communicate with each other by default. If they are in the same VPC but in different subnets or security groups, you must configure routing rules and security group rules. For details about how to configure routing rules, see configuring routes. For details about how to configure security group rules, see configuring security group rules.
- The MRS cluster and the DataArts Studio workspace belong to the same enterprise project. If they do not, you can modify the enterprise project of the workspace.

**Table 1** MRS HDFS link parameters
Parameter	Description	Example Value
Name	Link name, which should be defined based on the data source type, so it is easier to remember what the link is for	mrs_hdfs_link
Manager IP	Floating IP address of MRS Manager. Click Select next to the Manager IP text box to select an MRS cluster. CDM automatically fills in the authentication information.	127.0.0.1
Username	If Authentication Method is set to KERBEROS, you must provide the username and password used for logging in to MRS Manager. If you need to create a snapshot when exporting a directory from HDFS, the user configured here must have the administrator permission on HDFS. To create a data connection for an MRS security cluster, do not use user admin. The admin user is the default management page user and cannot be used as the authentication user of the security cluster. You can create an MRS user and set Username and Password to the username and password of the created MRS user when creating an MRS data connection. NOTE: If the CDM cluster version is 2.9.0 or later and the MRS cluster version is 3.1.0 or later, the created user must have the permissions of the Manager_viewer role to create links on CDM. To perform operations on databases, tables, and columns of an MRS component, you also need to add the database, table, and column permissions of the MRS component to the user by following the instructions in the MRS documentation. If the CDM cluster version is earlier than 2.9.0 or the MRS cluster version is earlier than 3.1.0, the created user must have the permissions of Manager_administrator or System_administrator to create links on CDM. A user with only the Manager_tenant or Manager_auditor permission cannot create connections.	cdm
Password	Password used for logging in to MRS Manager	-
Authentication Method	Authentication method used for accessing MRS SIMPLE: Select this for non-security mode. KERBEROS: Select this for security mode.	SIMPLE
Run Mode	Run mode of the HDFS link. The options are as follows: EMBEDDED: The link instance runs with CDM. This mode delivers better performance. STANDALONE: The link instance runs in an independent process. If CDM needs to connect to multiple Hadoop data sources (MRS, Hadoop, or CloudTable) with both Kerberos and Simple authentication modes, select STANDALONE or configure different agents. Note: The STANDALONE mode is used to solve the version conflict problem. If the connector versions of the source and destination ends of the same link are different, a JAR file conflict occurs. In this case, you need to place the source or destination end in the STANDALONE process to prevent the migration failure caused by the conflict. Agent: The link instance runs on an agent. If Agent is not used, and the CDM cluster connects to two or more clusters with Kerberos authentication enabled and the same realm, only one cluster can be connected in EMBEDDED mode, and the other clusters must be in STANDALONE mode.	STANDALONE
Agent	Click Select and select the agent created in Connecting to an Agent. This parameter is displayed when Run Mode is set to Agent.	-
Use Cluster Config	You can use the cluster configuration to simplify parameter settings for the Hadoop connection.	No
Cluster Config Name	This parameter is valid only when Use Cluster Config is set to Yes. Select a cluster configuration that has been created. For details, see Managing Cluster Configurations.	hdfs_01

Click Show Advanced Attributes, and then click Add to add configuration attributes of other clients. The name and value of each attribute must be configured. You can click Delete to delete no longer used attributes.

FusionInsight HDFS

When connecting CDM to HDFS of FusionInsight HD, configure the parameters as described in Table 2.

**Table 2** FusionInsight HDFS link parameters
Parameter	Description	Example Value
Name	Link name, which should be defined based on the data source type, so it is easier to remember what the link is for	FI_hdfs_link
Manager IP	IP address of FusionInsight Manager	127.0.0.1
Manager Port	Port number of FusionInsight Manager	28443
CAS Server Port	Port number of the CAS server used to connect to FusionInsight	20009
Username	Username used for logging in to FusionInsight Manager. If you need to create a snapshot when exporting a directory from HDFS, the user configured here must have the administrator permission on HDFS.	cdm
Password	Password used for logging in to FusionInsight Manager	-
Authentication Method	Authentication method used for accessing the cluster: SIMPLE: Select this for non-security mode. KERBEROS: Select this for security mode.	KERBEROS
Run Mode	Run mode of the HDFS link. The options are as follows: EMBEDDED: The link instance runs with CDM. This mode delivers better performance. STANDALONE: The link instance runs in an independent process. If CDM needs to connect to multiple Hadoop data sources (MRS, Hadoop, or CloudTable) with both Kerberos and Simple authentication modes, select STANDALONE or configure different agents. Note: The STANDALONE mode is used to solve the version conflict problem. If the connector versions of the source and destination ends of the same link are different, a JAR file conflict occurs. In this case, you need to place the source or destination end in the STANDALONE process to prevent the migration failure caused by the conflict. Agent: The link instance runs on an agent.	STANDALONE
Agent	Click Select and select the agent created in Connecting to an Agent. This parameter is displayed when Run Mode is set to Agent.	-
Use Cluster Config	You can use the cluster configuration to simplify parameter settings for the Hadoop connection.	No
Cluster Config Name	This parameter is valid only when Use Cluster Config is set to Yes. Select a cluster configuration that has been created. For details, see Managing Cluster Configurations.	hdfs_01

Apache HDFS

When connecting CDM to HDFS of Apache Hadoop, configure the parameters as described in Table 3.

**Table 3** Apache HDFS link parameters
Parameter	Description	Example Value
Name	Link name, which should be defined based on the data source type, so it is easier to remember what the link is for	hadoop_hdfs_link
URI	NameNode URI You can enter *hdfs://IP address of the NameNode instance:8020*.	hdfs://IP:8020
Authentication Method	Authentication method used for accessing the cluster: SIMPLE: Select this for non-security mode. KERBEROS: Select this for security mode.	KERBEROS
Principal	When Authentication Method is set to KERBEROS, this parameter is mandatory. It is the username in the Kerberos security mode and can be obtained from the Hadoop administrator. The value of this parameter must be the same as that in the Keytab file.	-
Keytab File	When Authentication Method is set to KERBEROS, a Keytab file must be uploaded. The Keytab file is an authentication credential and can be obtained from the Hadoop administrator. Before obtaining the keytab file, you need to change the password of this user at least once in the cluster. Otherwise, the downloaded keytab file may be unavailable. After a user password is changed, the exported keytab file becomes invalid, and you need to export a keytab file again.	-
Run Mode	Run mode of the HDFS link. The options are as follows: EMBEDDED: The link instance runs with CDM. This mode delivers better performance. STANDALONE: The link instance runs in an independent process. If CDM needs to connect to multiple Hadoop data sources (MRS, Hadoop, or CloudTable) with both Kerberos and Simple authentication modes, select STANDALONE or configure different agents. Note: The STANDALONE mode is used to solve the version conflict problem. If the connector versions of the source and destination ends of the same link are different, a JAR file conflict occurs. In this case, you need to place the source or destination end in the STANDALONE process to prevent the migration failure caused by the conflict. Agent: The link instance runs on an agent. For Apache HDFS, you can select Agent only if Authentication Method is set to SIMPLE.	STANDALONE
IP and Host Name Mapping	This parameter is used only when Run Mode is set to EMBEDDED or STANDALONE. If the HDFS configuration file uses the host name, configure the mapping between the IP address and host name. Separate the IP addresses and host names by spaces and mappings by semicolons (;), carriage returns, or line feeds.	10.1.6.9 hostname01 10.2.7.9 hostname02
Agent	If Run Mode is set to Agent, click Select and select the agent created in Connecting to an Agent.	-
Use Cluster Config	You can use the cluster configuration to simplify parameter settings for the Hadoop connection.	No
Cluster Config Name	This parameter is valid only when Use Cluster Config is set to Yes. Select a cluster configuration that has been created. For details, see Managing Cluster Configurations.	hdfs_01