Converting Volume Replication Type (High Throughput to Low Latency) Using the CLI

A low latency replication type allows for volumes to be replicated on multiple containers (in parallel) from the master container.

Note: Contact MapR Support before converting volumes to low_latency replication type.

To convert from a high-throughput to a low-latency replication type:

  1. Change the permissions on the volume from read-write to read only.
    For example:
    maprcli volume modify -name mvol1,mvol2 -readonly true
    Wait for the running operations to complete before proceeding to the next step.
  2. Convert the volume from high_throughput replication type to low_latency replication type using the maprcli command.
    For example:
    maprcli volume modify -name mvol1,mvol2 -replicationtype low_latency
    Wait till replication type conversion is complete and all the containers of the volume acquire a master. If necessary, run the following command to see if replication type has been converted:
    maprcli volume list -columns ReplTypeConversionInProgress,volumename
    If the conversion is complete, the ReplTypeConversionInProgress flag will be set to false (0). For example, the 0 in the ReplTypeConversionInProgress column in the following sample output indicates successful conversion of corresponding volume in the volumename column:
    # maprcli volume list -columns ReplTypeConversionInProgress,volumename
                            volumename                    ReplTypeConversionInProgress
                            mapr.apps                     0
                            mapr.cldb.internal            0
                            mapr.cluster.root             0
                            mapr.configuration            0
                            mapr.doc22.lab.local.audit    0
                            mapr.doc22.lab.local.logs     0
                            mapr.doc22.lab.local.mapred   0
                            mapr.doc22.lab.local.metrics  0
                            mapr.doc23.lab.local.audit    0
                            mapr.doc23.lab.local.logs     0
                            mapr.doc23.lab.local.mapred   0
                            mapr.doc23.lab.local.metrics  0
                            mapr.hbase                    0
                            mapr.metrics                  0
                            mapr.opt                      0
                            mapr.resourcemanager.volume   0
                            mapr.tmp                      0
                            mapr.var                      0
                            users                         0
  3. Reset the permissions on the volume to read-write.
    For example, to reset, run the following command:
    maprcli volume modify -name vol1,vol2 -readonly false