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diff --git a/doc/administration/geo/disaster_recovery/bring_primary_back.md b/doc/administration/geo/disaster_recovery/bring_primary_back.md new file mode 100644 index 00000000000..209ca2f50d0 --- /dev/null +++ b/doc/administration/geo/disaster_recovery/bring_primary_back.md @@ -0,0 +1,61 @@ +# Bring a demoted primary node back online + +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 1:** 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 2:** 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](https://gitlab.com/gitlab-org/gitlab-ee/blob/master/doc/gitlab-geo/planned-failover.md#block-primary-traffic) + > 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 |