About Release 7.9.0
This site contains documentation for HPE Ezmeral Data Fabric release 7.9.0, including installation, configuration, administration, and reference content, as well as content for the associated ecosystem components and drivers.
7.9.0 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.
7.9.0 Data Fabric
HPE Ezmeral Data Fabric is the industry-leading data platform for AI and analytics that solves enterprise business needs.
7.9.0 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 (ACEs) 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.
  - 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 Data Fabric 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.
- IPv6 Support in Data Fabric
  Describes the IPv6 support feature for Data Fabric.
7.9.0 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.

Retrieving the Number of Hard Links

Explains how to retrieve the number of hard links to a file.

To retrieve the number of hard links associated with a file, run the following command:

ls -l

The command, ls -l, will print the number of hardlinks in the second column. For example, your output will look similar to the following:

ls -l sample-link
  rw-r--r- 2 root root 0 Apr 21 11:09 sample-link

To retrieve the list of the hard links associated with a file, run the following command:

find <dirpath> -samefile <sourcefile>

where <dirpath> is the path to the source file and <sourcefile> is the source file for the hard link. For example, your output will look similar to the following:

find . -samefile file8
  ./file8-link2
  ./file8-link100
  ./file8-link101
  ./file8
  ./file8-link

For POSIX (loopback NFS for the HPE Ezmeral Data Fabric) clients, the number of hardlinks to a file can be retrieved using the stat64 system call. For example, your output will look similar to the following:

stat samplefile
  File: 'samplefile'
  Size: 0               Blocks: 0          IO Block: 131072 regular empty file
  Device: 14h/20d Inode: 853785146   Links: 4
  Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
  Access: 2016-05-12 13:06:21.000000000 -0700
  Modify: 2016-05-12 13:06:30.002560000 -0700
  Change: 2016-05-12 13:06:30.002560000 -0700

If you are not using NFS for the HPE Ezmeral Data Fabric or the POSIX clients, to retrieve the number of hard links, you can run the hadoop command to retrieve the fid and then run the maprcli command to retrieve the number of hard links as follows. The nlink variable will print the number of links.

hadoop mfs -ls /p1
  Found 1 items
  -rw-r--r--  Z U U   3 root root       3054 2016-05-05 13:49  268435456 /p1
  p 2049.40.262550  node-31.lab:5660

maprcli fid stat -fid 2049.40.262550
  xattrInum  uid  atime       nblocks  deleteFlags     mtime       parent     nlink  type       version  size  mode  networkencryption  subtype   gid  compression  
  0          0    1462481255  1        DeleteTypeNone  1462481376  2049.16.2  2      FTRegular  2097165  3054  644   false              FSTInval  0    lz4

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HPE Ezmeral Data Fabric – Customer-Managed 7.9.0 Documentation
Abstract	This site contains documentation for the customer-managed platform of the HPE Ezmeral Data Fabric version 7.9.0 including installation, configuration, administration, and reference content, as well as content for the associated bundled ecosystem components and drivers.
Published	November 2024
Edition	7.9.0