Chapter 5. Trusted Storage Pools

A storage pool is a network of storage servers.
When the first server starts, the storage pool consists of that server alone. Adding additional storage servers to the storage pool is achieved using the probe command from a running, trusted storage server.

Note

When any two gluster commands are executed concurrently on the same volume, the following error is displayed:
Another transaction is in progress.
This behavior in the Red Hat Storage server prevents two or more commands from simultaneously modifying a volume configuration, potentially resulting in an inconsistent state. Such an implementation is common in environments with monitoring frameworks such as the Red Hat Storage Console, Red Hat Enterprise Virtualization Manager, and Nagios. For example, in a four node Red Hat Storage Trusted Storage Pool, this message is observed when gluster volume status VOLNAME command is executed from two of the nodes simultaneously.

5.1. Adding Servers to the Trusted Storage Pool

The gluster peer probe [server] command is used to add servers to the trusted server pool.

Adding Three Servers to a Trusted Storage Pool

Create a trusted storage pool consisting of three storage servers, which comprise a volume.

Prerequisites

  • The glusterd service must be running on all storage servers requiring addition to the trusted storage pool. See Chapter 4, The glusterd Service for service start and stop commands.
  • Server1, the trusted storage server, is started.
  • The host names of the target servers must be resolvable by DNS.
  1. Run gluster peer probe [server] from Server 1 to add additional servers to the trusted storage pool.

    Note

    • Self-probing Server1 will result in an error because it is part of the trusted storage pool by default.
    • All the servers in the Trusted Storage Pool must have RDMA devices if either RDMA or RDMA,TCP volumes are created in the storage pool. The peer probe must be performed using IP/hostname assigned to the RDMA device.
    # gluster peer probe server2
    Probe successful
    
    # gluster peer probe server3
    Probe successful
    
    # gluster peer probe server4
    Probe successful
    
  2. Verify the peer status from all servers using the following command:
    # gluster peer status
    Number of Peers: 3
    
    Hostname: server2
    Uuid: 5e987bda-16dd-43c2-835b-08b7d55e94e5
    State: Peer in Cluster (Connected)
    
    Hostname: server3
    Uuid: 1e0ca3aa-9ef7-4f66-8f15-cbc348f29ff7
    State: Peer in Cluster (Connected)
    
    Hostname: server4
    Uuid: 3e0caba-9df7-4f66-8e5d-cbc348f29ff7
    State: Peer in Cluster (Connected)