E-MapReduce:Common commands for administrators

Prerequisites

Before you begin, ensure that you have:

• An EMR Hadoop cluster with Alluxio selected from optional services. For details, see Create a cluster.

• Logged on to the cluster. For details, see Log on to a cluster.

Commands overview

alluxio fsadmin supports the following subcommands:

For the full Admin Shell reference, see Admin Command Line Interface.

backup

Backs up Alluxio metadata to the specified directory. If no directory is specified, the backup is saved to the default path in Hadoop Distributed File System (HDFS).

Syntax:

alluxio fsadmin backup [directory]

Examples:

Back up metadata to the default directory:

alluxio fsadmin backup

Expected output:

Backup Host        : emr-header-1.cluster-23****
Backup URI         : hdfs://emr-header-1:9000/alluxio_backups/alluxio-backup-2021-06-01-1622547059762.gz
Backup Entry Count : 25

Back up metadata to the /tmp directory:

alluxio fsadmin backup /tmp

Expected output:

Backup Host        : emr-header-1.cluster-23****
Backup URI         : hdfs://emr-header-1:9000/tmp/alluxio-backup-2021-06-01-1622547072114.gz
Backup Entry Count : 25

doctor

Displays errors and alerts reported in Alluxio. Use this command to quickly check the health of your cluster.

Syntax:

alluxio fsadmin doctor [category]

The category parameter is optional. If omitted, all error and alert types are displayed.

Example:

alluxio fsadmin doctor

If no errors or warnings are detected, the output is:

All worker storage paths are in working state.

report

Displays status information about the Alluxio cluster.

Syntax:

alluxio fsadmin report [category]

The category parameter is optional. If omitted, only the cluster summary is displayed. Valid values: capacity, metrics, summary, ufs, and jobservice.

Example:

alluxio fsadmin report

The output is similar to:

Alluxio cluster summary:
    Master Address: emr-header-1:1****
    Web Port: 1****
    Rpc Port: 1****
    Started: 06-01-2021 14:07:08:420
    Uptime: 0 day(s), 20 hour(s), 42 minute(s), and 57 second(s)
    Version: 2.5.0
    Safe Mode: false
    Zookeeper Enabled: false
    Live Workers: 2
    Lost Workers: 0
    Total Capacity: 88.00GB
        Tier: MEM  Size: 8.00GB
        Tier: SSD  Size: 80.00GB
    Used Capacity: 320.00MB
        Tier: MEM  Size: 64.00MB
        Tier: SSD  Size: 256.00MB
    Free Capacity: 87.69GB

ufs

Updates the attributes of an attached underlying storage.

Syntax:

alluxio fsadmin ufs --mode <noAccess|readOnly|readWrite> <ufsPath>

Example:

Set the underlying storage to read-only mode to disallow write operations:

alluxio fsadmin ufs --mode readOnly hdfs://ns