debian-mirror-gitlab/doc/administration/geo/disaster_recovery/bring_primary_back.md

# Bring a demoted primary node back online **(PREMIUM ONLY)**

After a failover, it is possible to fail back to the demoted **primary** node to
restore your original configuration. This process consists of two steps:

1. Making the old **primary** node a **secondary** node.
1. Promoting a **secondary** node to a **primary** node.

CAUTION: **Caution:**
If you have any doubts about the consistency of the data on this node, we recommend setting it up from scratch.

## Configure the former **primary** node to be a **secondary** node

Since the former **primary** node will be out of sync with the current **primary** node, the first step is to bring the former **primary** node up to date. Note, deletion of data stored on disk like
repositories and uploads will not be replayed when bringing the former **primary** node back
into sync, which may result in increased disk usage.
Alternatively, you can [set up a new **secondary** GitLab instance][setup-geo] to avoid this.

To bring the former **primary** node up to date:

1. SSH into the former **primary** node that has fallen behind.
1. Make sure all the services are up:

   ```sh
   sudo gitlab-ctl start
   ```

   NOTE: **Note:** If you [disabled the **primary** node permanently][disaster-recovery-disable-primary],
   you need to undo those steps now. For Debian/Ubuntu you just need to run
   `sudo systemctl enable gitlab-runsvdir`. For CentOS 6, you need to install
   the GitLab instance from scratch and set it up as a **secondary** node by
   following [Setup instructions][setup-geo]. In this case, you don't need to follow the next step.

   NOTE: **Note:** If you [changed the DNS records](index.md#step-4-optional-updating-the-primary-domain-dns-record)
   for this node during disaster recovery procedure you may need to [block
   all the writes to this node](planned_failover.md#prevent-updates-to-the-primary-node)
   during this procedure.

1. [Setup database replication][database-replication]. Note that in this
   case, **primary** node refers to the current **primary** node, and **secondary** node refers to the
   former **primary** node.

If you have lost your original **primary** node, follow the
[setup instructions][setup-geo] to set up a new **secondary** node.

## Promote the **secondary** node to **primary** node

When the initial replication is complete and the **primary** node and **secondary** node are
closely in sync, you can do a [planned failover].

## Restore the **secondary** node

If your objective is to have two nodes again, you need to bring your **secondary**
node back online as well by repeating the first step
([configure the former **primary** node to be a **secondary** node](#configure-the-former-primary-node-to-be-a-secondary-node))
for the **secondary** node.

[setup-geo]: ../replication/index.md#setup-instructions
[database-replication]: ../replication/database.md
[disaster-recovery-disable-primary]: index.md#step-2-permanently-disable-the-primary-node
[planned failover]: planned_failover.md