5.10. Creating Distributed Dispersed Volumes

Distributed dispersed volumes support the same configurations of erasure coding as dispersed volumes. The number of bricks in a distributed dispersed volume must be a multiple of (K+M). With this release, the following configurations are supported:
  • Multiple disperse sets containing 6 bricks with redundancy level 2
  • Multiple disperse sets containing 10 bricks with redundancy level 2
  • Multiple disperse sets containing 11 bricks with redundancy level 3
  • Multiple disperse sets containing 12 bricks with redundancy level 4
  • Multiple disperse sets containing 20 bricks with redundancy level 4

Important

Distributed dispersed volume configuration is supported only on JBOD storage. For more information, see Section 21.1.2, “JBOD”.
Use gluster volume create to create different types of volumes, and gluster volume info to verify successful volume creation.
Prerequisites
Illustration of a Distributed Dispersed Volume

Figure 5.8. Illustration of a Distributed Dispersed Volume

Creating distributed dispersed volumes

Important

Red Hat recommends you to review the Distributed Dispersed Volume configuration recommendations explained in Section 11.12, “Recommended Configurations - Dispersed Volume” before creating the Distributed Dispersed volume.
  1. Run the gluster volume create command to create the dispersed volume.
    The syntax is # gluster volume create NEW-VOLNAME disperse-data COUNT [redundancy COUNT] [transport tcp | rdma | tcp,rdma] NEW-BRICK...
    The default value for transport is tcp. Other options can be passed such as auth.allow or auth.reject. See Section 11.1, “Configuring Volume Options” for a full list of parameters.

    Example 5.12. Distributed Dispersed Volume with Six Storage Servers

    # gluster volume create test-volume disperse-data 4 redundancy 2 transport tcp server1:/rhgs1/brick1 server2:/rhgs2/brick2 server3:/rhgs3/brick3 server4:/rhgs4/brick4 server5:/rhgs5/brick5 server6:/rhgs6/brick6 server1:/rhgs7/brick7 server2:/rhgs8/brick8 server3:/rhgs9/brick9 server4:/rhgs10/brick10 server5:/rhgs11/brick11 server6:/rhgs12/brick12
    Creation of test-volume has been successful
    Please start the volume to access data.
    The above example is illustrated in Figure 5.7, “Illustration of a Dispersed Volume” . In the illustration and example, you are creating 12 bricks from 6 servers.
  2. Run # gluster volume start VOLNAME to start the volume.
    # gluster volume start test-volume
    Starting test-volume has been successful

    Important

    The open-behind volume option is enabled by default. If you are accessing the distributed dispersed volume using the SMB protocol, you must disable the open-behind volume option to avoid performance bottleneck on large file workload. Run the following command to disable open-behind volume option:
    # gluster volume set VOLNAME open-behind off
    For information on open-behind volume option, see Section 11.1, “Configuring Volume Options”
  3. Run gluster volume info command to optionally display the volume information.