HPE Ezmeral Data Fabric 6.2 is In Maintenance and transitions to "End of Maintenance" in June 2024. Please see the latest documentation.

About Release 6.2
This site contains documentation for HPE Ezmeral Data Fabric release 6.2 including installation, configuration, administration, and reference content, as well as content for the associated bundled ecosystem components and drivers.
6.2 Installation
This section contains information about installing and upgrading HPE Ezmeral Data Fabric software. It also contains information about how to migrate data and applications from an Apache Hadoop cluster to a HPE Ezmeral Data Fabric cluster.
6.2 Data Fabric
HPE Ezmeral Data Fabric is the industry-leading data platform for AI and analytics that solves enterprise business needs.
6.2 Administration
This section describes how to manage the nodes and services that make up a cluster.
- Administering Users and Clusters
  Lists topics that help manage a data-fabric cluster.
- Administering Nodes
  Provides a synopsis of managing nodes in a cluster.
- Administering Volumes
  This section provide information about how to organize and manage data using volumes, a unique feature of HPE Ezmeral Data Fabric clusters.
- Administering Files and Directories
  - Using Global File System Checking
    Describes how to use the gfsck command to check and repair file system errors.
  - Setting file system Permissions
  - Managing File and Directory ACEs
    Describes the implications of setting access control expressions on files and directories.
  - Managing Chunk Size
    Describes the considerations for managing the chunk size for map tasks.
  - Managing Compression
    Lists the advantages of using compression.
  - Managing Hard Links
    Explains what hard links are, and their limitations.
    - Enabling Hard Links
    - Setting a Hard Link
      Explains how to create a hardlink to a file.
    - Retrieving the Number of Hard Links
      Explains how to retrieve the number of hard links to a file.
    - Removing Hard Links
  - Managing Extended Attributes
    Describes what extended attributes are, and the POSIX permissions that you need to manage them.
  - Managing Core Files
    Describes how to set the location for core files.
  - Migrating Files from the Edge Cluster to AWS S3
    Describes how new or changed files are automatically uploaded to AWS S3 by the File Migration service.
  - Managing Tiered Files from the Command-line
- Administering Tables
  Administration of the HPE Ezmeral Data Fabric Database is done primarily via the command line (maprcli) or with the Managed Control System (MCS). Regardless of whether the HPE Ezmeral Data Fabric Database table is used for binary files or JSON documents, the same types of commands are used with slightly different parameter options. HPE Ezmeral Data Fabric Database administration is associated with tables, columns and column families, and table regions.
- Administering Streams
- Administering Data Fabric Gateways
  A HPE Ezmeral Data Fabric gateway mediates one-way communication between a source HPE Ezmeral Data Fabric cluster and a destination cluster. You can replicate HPE Ezmeral Data Fabric Database tables (binary and JSON) and HPE Ezmeral Data Fabric Streams streams. HPE Ezmeral Data Fabric gateways also apply updates from JSON tables to their secondary indexes and propagate Change Data Capture (CDC) logs.
- Administering Services
- Monitoring the Cluster
  This section describes how to monitor the health and performance of a MapR cluster.
- Configuring Security
  Describes how to configure security and manage secure clusters.
- Managing Secure Clusters
  Provides procedures that will enable you to use MapR clusters securely.
- Administering the Data Access Gateway
  The HPE Ezmeral Data Fabric Data Access Gateway is a service that acts as a proxy and gateway for translating requests between lightweight client applications and the HPE Ezmeral Data Fabric cluster. This section describes considerations when upgrading the service, how to modify configuration settings, and how to administer and manage the service.
- Planning for High Availability
- Administrator's Reference
  This section contains in-depth reference information for the administrator.
- Troubleshooting Cluster Administration
  Lists the common errors and their solutions.
- Best Practices for Backing Up HPE Ezmeral Data Fabric Information
  Lists the best practices and performance considerations to follow when backing up HPE Ezmeral Data Fabric information.
6.2 Development
This section contains information related to application development for Ezmeral ecosystem components and HPE Ezmeral Data Fabric products, including the file system, Database (Key-Value and JSON), and Event Streams.
Other Docs
This section contains release-independent information, including: Installer documentation, Ecosystem release notes, interoperability matrices, security vulnerabilities, and links to other data-fabric version documentation.
Glossary
Definitions for commonly used terms in MapR Converged Data Platform environments.

Removing Hard Links

To remove a hard link using:

Linux, run the following command:
```
rm -f <hard link>
```
Hadoop, run the following command:
```
hadoop fs -rm <path to hard link>
```

Example

For example, suppose there are 4 hard links to file cite75_99.txt.

$ ls -l
total 1289433
-rwxr-xr-x 5 root root 264075431 Jul 28 13:46 cite75_99.txt
-rwxr-xr-x 5 root root 264075431 Jul 28 13:46 cite-link1
-rwxr-xr-x 5 root root 264075431 Jul 28 13:46 cite-link2
-rwxr-xr-x 5 root root 264075431 Jul 28 13:46 cite-link3
-rwxr-xr-x 5 root root 264075431 Jul 28 13:46 cite-link4

$ maprcli fid stat -fid 2142.34.131274
parent     deleteFlags     atime       gid  nlink  type       mtime       version  mode  uid  xattrInum  size       subtype   networkencryption  nblocks  compression
2142.16.2  DeleteTypeNone  1469738740  0    5      FTRegular  1469738771  1048600  755   0    0          264075431  FSTInval  false              8        lz4

To remove a hard link using:

Linux, run the following command:

rm -f cite-link1

To verify that the command ran successfully, run the following command:

$ ls -l
total 1031546
-rwxr-xr-x 4 root root 264075431 Jul 28 13:46 cite75_99.txt
-rwxr-xr-x 4 root root 264075431 Jul 28 13:46 cite-link2
-rwxr-xr-x 4 root root 264075431 Jul 28 13:46 cite-link3
-rwxr-xr-x 4 root root 264075431 Jul 28 13:46 cite-link4

Hadoop, run the following command:

$ hadoop fs -rm /test-hl/cite-link2
16/07/28 13:52:00 INFO Configuration.deprecation: io.bytes.per.checksum is deprecated. Instead, use dfs.bytes-per-checksum
16/07/28 13:52:00 INFO fs.TrashPolicyDefault: Namenode trash configuration: Deletion interval = 0 minutes, Emptier interval = 0 minutes.
Deleted /test-hl/cite-link2

To verify that the command ran successfully, run the following command:

$ maprcli fid stat -fid 2142.34.131274
parent  deleteFlags     atime       gid  nlink  type       mtime       version  mode  uid  xattrInum  size       subtype   networkencryption  nblocks  compression
0.0.0   DeleteTypeNone  1469738740  0    3      FTRegular  1469738771  1048603  755   0    0          264075431  FSTInval  false              8        lz4