11.12. Setting up Shared Storage Volume

Features like Snapshot Scheduler, NFS Ganesha and geo-replication require a shared storage to be available across all nodes of the cluster. A gluster volume named gluster_shared_storage is made available for this purpose, and is facilitated by the following volume set option.
cluster.enable-shared-storage
This option accepts the following two values:
  • enable

    When the volume set option is enabled, a gluster volume named gluster_shared_storage is created in the cluster, and is mounted at /var/run/gluster/shared_storage on all the nodes in the cluster.

    Note

    • This option cannot be enabled if there is only one node present in the cluster, or if only one node is online in the cluster.
    • The volume created is either a replica 2, or a replica 3 volume. This depends on the number of nodes which are online in the cluster at the time of enabling this option and each of these nodes will have one brick participating in the volume. The brick path participating in the volume is /var/lib/glusterd/ss_brick.
    • The mount entry is also added to /etc/fstab as part of enable.
    • Before enabling this feature make sure that there is no volume named gluster_shared_storage in the cluster. This volume name is reserved for internal use only
    After successfully setting up the shared storage volume, when a new node is added to the cluster, the shared storage is not mounted automatically on this node. Neither is the /etc/fstab entry added for the shared storage on this node. To make use of shared storage on this node, execute the following commands:
    # mount -t glusterfs <local node's ip>:gluster_shared_storage
    /var/run/gluster/shared_storage
    # cp /etc/fstab /var/run/gluster/fstab.tmp
    # echo "<local node's ip>:/gluster_shared_storage
    /var/run/gluster/shared_storage/ glusterfs defaults 0 0" >> /etc/fstab
  • disable

    When the volume set option is disabled, the gluster_shared_storage volume is unmounted on all the nodes in the cluster, and then the volume is deleted. The mount entry from /etc/fstab as part of disable is also removed.

For example:
# gluster volume set all cluster.enable-shared-storage enable
volume set: success

Important

After creating a cluster excute the following command on all nodes present in the cluster:
systemctl enable glusterfssharedstorage.service
This is applicable for Red Hat Enterpise Linux 7 only.