Hadoop Snapshot Operations Test

HDFS Snapshots are read-only point-in-time copies of the file system. Snapshots can be taken on a subtree of the file system or the entire file system. Some common use cases of snapshots are data backup, protection against user errors and disaster recovery.

Using the Hadoop Snapshot Operations test, administrators can track administrator- and user-initiated snapshot operations on the HDFS.

Target of the test : A Hadoop cluster

Agent deploying the test : A remote agent

Outputs of the test : One set of the results for the Hadoop cluster being monitored

Configurable parameters for the test
Parameter Description

Test Period

How often should the test be executed.

Host

The IP address of the NameNode that processes client connections to the cluster. NameNode is the master node in the Apache Hadoop HDFS Architecture that maintains and manages the blocks present on the DataNodes (slave nodes). NameNode is a very highly available server that manages the File System Namespace and controls access to files by clients.

Port

The port at which the NameNode accepts client connections. NameNode is the master node in the Apache Hadoop HDFS Architecture that maintains and manages the blocks present on the DataNodes (slave nodes). NameNode is a very highly available server that manages the File System Namespace and controls access to files by clients. By default, the NameNode's client connection port is 8020.

Name Node Web Port

The eG agent collects metrics using Hadoop's WebHDFS REST API. While some of these API calls pull metrics from the NameNode, some others get metrics from the resource manager. NameNode is the master node in the Apache Hadoop HDFS Architecture that maintains and manages the blocks present on the DataNodes (slave nodes). NameNode is a very highly available server that manages the File System Namespace and controls access to files by clients. To run API commands on the NameNode and pull metrics, the eG agent needs access to the NameNode's web port.

To determine the correct web port of the NameNode, do the following:

  • Open the hdfs-default.xml file in the hadoop/conf/app directory.
  • Look for the dfs.namenode.http-address parameter in the file.
  • This parameter is configured with the IP address and base port where the DFS NameNode web user interface listens on. The format of this configuration is: <IP_Address>:<Port_Number>. Given below is a sample configuration:

    192.168.10.100:50070

Configure the <Port_Number> in the specification as the Name Node Web Port. In the case of the above sample configuration, this will be 50070.

Name Node User Name

The eG agent collects metrics using Hadoop's WebHDFS REST API. While some of these API calls pull metrics from the NameNode, some others get metrics from the resource manager. NameNode is the master node in the Apache Hadoop HDFS Architecture that maintains and manages the blocks present on the DataNodes (slave nodes). NameNode is a very highly available server that manages the File System Namespace and controls access to files by clients.

In some Hadoop configurations, a simple authentication user name may be required for running API commands and collecting metrics from the NameNode. When monitoring such Hadoop installations, specify the name of the simple authentication user here. If no such user is available/required, then do not disturb the default value none of this parameter.

Resource  Manager IP and Resource Manager Web Port

The eG agent collects metrics using Hadoop's WebHDFS REST API. While some of these API calls pull metrics from the NameNode, some others get metrics from the resource manager. The YARN Resource Manager Service (RM) is the central controlling authority for resource management and makes resource allocation decisions.

To pull metrics from the resource manager, the eG agents first needs to connect to the resource manager. For this, you need to configure this test with the IP address/host name of the resource manager and its web port. Use the Resource Manager IP and Resource Manager Web Port parameters to configure these details.

To determine the IP/host name and web port of the resource manager, do the following:

  • Open the yarn-site.xml file in the /opt/mapr/hadoop/hadoop-2. x.x/etc/hadoop directory.
  • Look for the yarn.resourcemanager.webapp.address parameter in the file.
  • This parameter is configured with the IP address/host name and web port of the resource manager. The format of this configuration is: <IP_Address_or_Host_Name>:<Port_Number>. Given below is a sample configuration:

    192.168.10.100:8080

Configure the <IP_Address_or_Host_Name> in the specification as the Resource Manager IP, and the <Port_Number> as the Resource Manager Web Port. In the case of the above sample configuration, this will be 8080.

Resource Manager Username

The eG agent collects metrics using Hadoop's WebHDFS REST API. While some of these API calls pull metrics from the NameNode, some others get metrics from the resource manager. The YARN Resource Manager Service (RM) is the central controlling authority for resource management and makes resource allocation decisions.

In some Hadoop configurations, a simple authentication user name may be required for running API commands and collecting metrics from the resource manager. When monitoring such Hadoop installations, specify the name of the simple authentication user here. If no such user is available/required, then do not disturb the default value none of this parameter.

Measurements made by the test
Measurement Description Measurement Unit Interpretation

Allow operations

Indicates the rate at which Allow Snapshots operations were performed on the HDFS.

Operations/Sec

The Allow Snapshots operation allows snapshots of a directory to be created. If the operation is successful, the directory becomes snapshottable.

Superuser privileges are required for performing this operation.

Disallow operations

Indicates the rate at which Disallow Snapshots operations were performed on the HDFS.

Operations/Sec

The Disallow Snapshots operations disallows the creation of snapshots for a directory. All snapshots of the directory must be deleted before disallowing snapshots.

Superuser privileges are required for performing this operation.

Create operations

Indicates the rate at which Create Snapshots operations were performed on the HDFS.

Operations/Sec

Use this operation to create a snapshot of a snapshottable directory. Owner privilege of the snapshottable directory are required for performing this operation.

Delete Snapshots

Indicates the rate at which Delete Snapshots operations were performed on the HDFS.

Operations/Sec

This operation deletes a snapshot of a om a snapshottable directory. Owner privilege of the snapshottable directory are required for performing this operation.

Rename Snapshots

Indicates the rate at which Delete Snapshots operations were performed on the HDFS.

Operations/Sec

This operation renames a snapshot. Owner privilege of the snapshottable directory are required for performing this operation.