14.3. Preparing to Deploy Geo-replication

Creating Geo-replication Sessions

1. To create a common pem pub file, run the following command on the master node where the passwordless SSH connection is configured:

   # gluster system:: execute gsec_create

2. Create the geo-replication session using the following command. The push-pem option is needed to perform the necessary pem-file setup on the slave nodes.

   # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL create push-pem [force]

   For example:

   # gluster volume geo-replication Volume1 example.com::slave-vol create push-pem

   Note

   There must be passwordless SSH access between the node from which this command is run, and the slave host specified in the above command. This command performs the slave verification, which includes checking for a valid slave URL, valid slave volume, and available space on the slave. If the verification fails, you can use the force option which will ignore the failed verification and create a geo-replication session.
3. Configure the meta-volume for geo-replication:

   # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL config use_meta_volume true

   For example:

   # gluster volume geo-replication Volume1 example.com::slave-vol config use_meta_volume true

   For more information on configuring meta-volume, see Section 14.3.5, “Configuring a Meta-Volume”.
4. Start the geo-replication by running the following command on the master node:
   For example,

   # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL start [force]

5. Verify the status of the created session by running the following command:

   # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL status

1. Create a new group. For example, geogroup.
2. Create a unprivileged account. For example, geoaccount. Add geoaccount as a member of geogroup group.
3. As a root, create a new directory with permissions 0711 and with correct SELinux context. Ensure that the location where this directory is created is writeable only by root but geoaccount is able to access it.
   For example,

   # mkdir /var/mountbroker-root
   # chmod 0711 /var/mountbroker-root
   # semanage fcontext -a -e /home /var/mountbroker-root
   # restorecon -Rv /var/mountbroker-root

4. Run the following commands in any one of the Slave node:

   # gluster system:: execute mountbroker opt mountbroker-root /var/mountbroker-root
   # gluster system:: execute mountbroker user geoaccount slavevol
   # gluster system:: execute mountbroker opt geo-replication-log-group geogroup
   # gluster system:: execute mountbroker opt rpc-auth-allow-insecure on

   See Section 2.4, “Storage Concepts” for information on glusterd.vol volume file of a Red Hat Gluster Storage volume.
   If the above commands fails, check if the glusterd.vol file is available at /etc/glusterfs/ directory. If not found, create a glusterd.vol file containing the default configuration and save it at /etc/glusterfs/ directory. Now re-run the above commands listed above to get all the required geo-replication options.
   The following is the sample glusterd.vol file along with default options:

   volume management
       type mgmt/glusterd
       option working-directory /var/lib/glusterd
       option transport-type socket,rdma
       option transport.socket.keepalive-time 10
       option transport.socket.keepalive-interval 2
       option transport.socket.read-fail-log off
       option rpc-auth-allow-insecure on
       
       option mountbroker-root /var/mountbroker-root 
       option mountbroker-geo-replication.geoaccount slavevol
       option geo-replication-log-group geogroup
   end-volume

   • If you have multiple slave volumes on Slave, repeat Step 2 for each of them and run the following commands to update the vol file:

     # gluster system:: execute mountbroker user geoaccount2 slavevol2
     # gluster system:: execute mountbroker user geoaccount3 slavevol3

     You can use gluster system:: execute mountbroker info command to view the configured mountbroker options.
   • You can add multiple slave volumes within the same account (geoaccount) by providing comma-separated list (without spaces) as the argument of mountbroker-geo-replication.geogroup. You can also have multiple options of the form mountbroker-geo-replication.*. It is recommended to use one service account per Master machine. For example, if there are multiple slave volumes on Slave for the master machines Master1, Master2, and Master3, then create a dedicated service user on Slave for them by repeating Step 2. for each (like geogroup1, geogroup2, and geogroup3), and then run the following commands to add the corresponding options to the volfile:

     # gluster system:: execute mountbroker user geoaccount1 slavevol11,slavevol12,slavevol13
     # gluster system:: execute mountbroker user geoaccount2 slavevol21,slavevol22
     # gluster system:: execute mountbroker user geoaccount3 slavevol31

5. Restart glusterd service on all the Slave nodes.
   After you setup an auxiliary glusterFS mount for the unprivileged account on all the Slave nodes, perform the following steps to setup a non-root geo-replication session.:
6. Setup a passwordless SSH from one of the master node to the user on one of the slave node.
   For example, to setup a passwordless SSH to the user geoaccount.

   # ssh-keygen
   # ssh-copy-id -i identity_file geoaccount@slave_node_IPaddress/Hostname

7. Create a common pem pub file by running the following command on the master node where the passwordless SSH connection is configured to the user on the slave node:

   # gluster system:: execute gsec_create

8. Create a geo-replication relationship between master and slave to the user by running the following command on the master node:
   For example,

   # gluster volume geo-replication MASTERVOL geoaccount@SLAVENODE::slavevol create push-pem

   If you have multiple slave volumes and/or multiple accounts, create a geo-replication session with that particular user and volume.
   For example,

   # gluster volume geo-replication MASTERVOL geoaccount2@SLAVENODE::slavevol2 create push-pem

9. In the slavenode, which is used to create relationship, run /usr/libexec/glusterfs/set_geo_rep_pem_keys.sh as a root with user name, master volume name, and slave volume names as the arguments.
   For example,

    # /usr/libexec/glusterfs/set_geo_rep_pem_keys.sh geoaccount MASTERVOL SLAVEVOL_NAME 

10. Configure the meta-volume for geo-replication:

    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL config use_meta_volume true

    For example:

    # gluster volume geo-replication Volume1 example.com::slave-vol config use_meta_volume true

    For more information on configuring meta-volume, see Section 14.3.5, “Configuring a Meta-Volume”.
11. Start the geo-replication with slave user by running the following command on the master node:
    For example,

    # gluster volume geo-replication MASTERVOL geoaccount@SLAVENODE::slavevol start

12. Verify the status of geo-replication session by running the following command on the master node:

    # gluster volume geo-replication MASTERVOL geoaccount@SLAVENODE::slavevol status