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5.1 Reference
This section provides information about development content including MapR-FS and MapReduce development topics and reference content.
Reference Guide
maprcli and REST API Syntax
volume
Manages volumes, snapshots and mirrors.
volume mirror start
Starts mirroring on the specified volume from its source volume.

MapR 5.1 Documentation

5.1 Reference
This section provides information about development content including MapR-FS and MapReduce development topics and reference content.
- Development Guide
- Reference Guide
  - MapR Control System
  - Hadoop Commands
  - HBase Shell for MapR-DB
    You can manage MapR-DB tables using HBase shell commands and additional HBase shell commands included in the MapR distribution of Hadoop.
  - YARN commands
  - maprcli and REST API Syntax
    - Overview
      Each command reference page includes the command syntax, a table that describes the parameters, and examples of command usage.
    - acl
      Describes the acl commands used to access control lists (ACLs).
    - alarm
      Describes the alarm commands that perform functions related to system alarms.
    - audit
      Describes commands used to audit operations related to cluster management and data access.
    - blacklist
      Describes commands used to blacklist and to list blacklisted users.
    - cluster
      Manages cluster features, gateways, and cluster-wide settings.
    - config
      Manages configuration values for the MapR cluster.
    - dashboard info
      Displays a summary of information about the cluster.
    - dialhome
    - disk
      Describes command for working with disks.
    - dump
      Returns key information about volumes, containers, storage pools, and MapR cluster services for debugging and troubleshooting.
    - entity
      Manages entities (users and groups).
    - fid
      Displays information about MapR-DB or file-system components that are identified by a FID.
    - job
      Manages Hadoop jobs running on the cluster.
    - license
      Manages MapR licenses.
    - nagios generate
      Generates a Nagios Object Definition file that describes the cluster nodes and the services running on each.
    - nfsmgmt
      Refreshes NFS exports and server cache.
    - node
      Manages nodes in the cluster
    - rlimit
      Manages resource usage limits for the cluster.
    - schedule
      Manages schedules.
    - service list
      Lists all services on the specified node, the memory allocated for each service, the state of each service, and log path for each service.
    - setloglevel
      Sets log level on individual services.
    - stream
      Manages stream functionality.
    - table
      Performs functions related to MapR-DB tables.
    - task
      Manipulates information about the Hadoop jobs that are running on your cluster.
    - trace
      Lets you view and modify the trace buffer, and the trace levels for the system modules.
    - urls
      Displays the status page URL for the specified service.
    - virtualip
      Manages virtual IP addresses for NFS nodes.
    - volume
      Manages volumes, snapshots and mirrors.
      - volume audit
        Enables or disables auditing on the specified volume.
      - volume container move
        Moves a container. Permissions required: fc or m on the volume.
      - volume container switchmaster
        Switches the master replica for a specified container to another replica in the replica chain.
      - volume create
        Creates a volume. Permissions required: cv or fc on the volume.
      - volume dump create
        Creates a volume dump file containing data from a volume for distribution or restoration. Permissions required: dump or fc on the volume.
      - volume dump restore
        Restores or updates a volume from a dump file. Permissions required: fc or restore on the volume.
      - volume fixmountpath
        Corrects the mount path of a volume. Permissions required: fc or m on the volume.
      - volume info
        Displays information about the specified volume. For best results, use the -json option when running the command.
      - volume link create
        Creates a link to a volume. Permissions required: fc or m on the volume.
      - volume link remove
        Removes the specified symbolic link. Permissions required: fc or m on the volume.
      - volume list
      - volume mirror push
        Pushes the changes in a volume to all of its mirror volumes in the same cluster, and waits for each mirroring operation to complete.
      - volume mirror start
        Starts mirroring on the specified volume from its source volume.
      - volume mirror stop
        Stops mirroring on the specified volume.
      - volume modify
        Modifies an existing volume. Permissions required: m or fc on the volume.
      - volume mount
        Mounts one or more specified volumes. Permissions required: fc or m on the volume.
      - volume move
        Moves the specified volume or mirror to a different topology. Permissions required: m or fc on the volume.
      - volume remove
        Removes the specified volume or mirror. Permissions required: d or fc on the volume.
      - volume rename
        Renames the specified volume or mirror. Permissions required: fc or d on the volume.
      - volume showmounts
        Returns a list of mount points for the specified volume.
      - volume snapshot create
        Creates a snapshot of the specified volume, using the specified snapshot name.
      - volume snapshot list
        Displays info about a set of snapshots.
      - volume snapshot preserve
        Preserves one or more snapshots from expiration.
      - volume snapshot remove
        Removes one or more snapshots.
      - volume unmount
        Unmounts one or more mounted volumes. Permissions required: fc or m on the volume.
      - volume upgradeformat
        Upgrades and old-type volume to a new-type volume, which can in turn be used as a promotable mirror volume. Permissions required: m or fc on the volume.
  - Alarms Reference
  - Utilities
  - Default MapR Configurations
  - Configuration Files
  - MapR Environment
  - MapR Parameters
  - Best Practices
  - Language Support for MapR-DB Tables
  - Glossary
    This section contains defintions for commonly used terms in MapR Converged Data Platform environments.
  - Source Code for MapR Software
- Glossary
  This section contains defintions for commonly used terms in MapR Converged Data Platform environments.

volume mirror start

Starts mirroring on the specified volume from its source volume.

License required: Enterprise Edition
Permissions required: fc or restore on the volume

When a mirror is started, the mirror volume is synchronized from a hidden internal snapshot so that the mirroring process is not affected by any concurrent changes to the source volume. The volume mirror start command does not wait for mirror completion, but returns immediately. The changes to the mirror volume occur atomically at the end of the mirroring process; deltas transmitted from the source volume do not appear until mirroring is complete.

To provide rollback capability for the mirror volume, the mirroring process creates a snapshot of the mirror volume before starting the mirror, with the following naming format: <volume>.mirrorsnap.<date>.<time>.

Normally, the mirroring operation transfers only deltas from the last successful mirror. Under certain conditions (mirroring a volume repaired by fsck, for example), the source and mirror volumes can become out of sync. In such cases, it is impossible to transfer deltas, because the state is not the same for both volumes. Use the -full option to force the mirroring operation to transfer all data to bring the volumes back in sync.

Syntax

CLI

maprcli volume mirror start
    [ -cluster <cluster> ]
    [ -full true|false ]
    -name <volume name>

REST

http[s]://<host>:<port>/rest/volume/mirror/start?<parameters>

Parameters

Parameter	Description
cluster	The cluster on which to run the command.
full	Specifies whether to perform a full copy of all data. If false, only the deltas are copied.
name	The volume for which to start the mirror.

Output

Sample Output

messages                                            
Started mirror operation for volumes 'testMirror'

Examples

Start mirroring the mirror volume "testMirror":

CLI

maprcli volume mirror start -name testMirror

REST

https://centos26.lab:8443/rest/volume/mirror/start?name=testMirror