.. _Enabling Backup Gateway Geo-Replication:

Enabling Backup Gateway Geo-Replication
---------------------------------------

Make sure the following prerequisites are met:

- Two or more storage clusters with ABGW are deployed.
- All storage clusters are updated to the latest version.
- All storage clusters can ping each other via IP addresses or domain names on port 44445.
- All storage clusters are registered in Acronis Backup Cloud.

To set up geo-replication between two storage clusters, a master and a slave, do the following:

#. Find out the ``dc_uid`` values from ``/mnt/vstorage/vols/acronis-backup/conf.d/dc_uid`` on both the master and the slave.

#. Copy the ``/mnt/vstorage/vols/acronis-backup/certs/abgw.pem`` files from both the master and the slave to a machine from which you will configure replication (i.e. run ``vstorage-abgw-ctl``). For example, to ``master_abgw.pem`` and ``slave_abgw.pem``, respectively.

#. Configure replication:

   ::

       # vstorage-abgw-ctl replication \
       --master-addr <master_DNS_name> --master-cert master_abgw.pem --master-uid <master_dc_uid> \
       --slave-addr <slave_DNS_name> --slave-cert slave_abgw.pem --slave-uid <slave_dc_uid> \
       --enable /<account-name>

This command will enable replication of existing files. If new files are added to an account, the command will need to be re-run. For more convenience, you can set up a cron job that will run the following script automatically on one of the storage nodes:

::

   #!/bin/bash

   cd /mnt/vstorage/vols/acronis-backup/storage
   for dir in *; do
     vstorage-abgw-ctl replication \
       --master-addr <master_DNS_name> --master-cert master_abgw.pem --master-uid <master_dc_uid> \
       --slave-addr <slave_DNS_name> --slave-cert slave_abgw.pem --slave-uid <slave_dc_uid> \
       --enable /$dir
   done

If PEM certificates expire, update them in the web interface and exchange them between clusters once again.

If a failover to the slave replica is needed, contact the technical support team. A tool for performing unassisted failovers will be added in a future update.

.. only:: ac

   With geo-replication set up, clusters exchange data as pictured on the diagram.
   
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      .. image:: /images/stor_image147_ac.png
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   .. only:: latex
   
      .. image:: /images/stor_image147_ac.pdf
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   Where ``<ext_IP>`` are external IP addresses of each cluster. The DNS configuration will be as follows:

   - primary-storage.mysite.domain will resolve to 1.2.3.4, 1.2.3.5, etc. (external IP addresses of cluster #1)
   - secondary-storage.mysite.domain will resolve to 5.6.7.8, 5.6.7.9, etc. (public IP addresses of cluster #2)

   In your Acronis Data Cloud admin panel, on the **SETTINGS** > **Locations** screen, you can see configuration like this:
   
   .. image:: /images/stor_image148_ac.png
      :align: center
      :class: align-center