Starting a geo-replication session activates asynchronous replication between the primary and secondary GlusterFS volumes. A running session continuously synchronizes file changes, keeping the secondary volume usable for disaster recovery and offsite redundancy.

Geo-replication is configured at the volume level and remains inactive until a start operation launches its workers. On the primary cluster, gsyncd processes scan the primary bricks, transfer data over SSH, and keep metadata and contents synchronized with the secondary volume.

The first start commonly triggers an initial full crawl that can be expensive for volumes with many files. Ensure the session is already created and the geo-replication account can authenticate to the secondary without interactive prompts, then monitor crawl progress and errors during the first synchronization window.

Steps to start a GlusterFS geo-replication session:

  1. Start the geo-replication session on the primary cluster.
    $ sudo gluster volume geo-replication gvol-primary geoaccount@snode1.example.com::gvol-secondary start
    geo-replication: start: success

    Initial synchronization can increase disk I/O and network utilization on both clusters.

  2. Check the session status after the start command completes.
    $ sudo gluster volume geo-replication gvol-primary geoaccount@snode1.example.com::gvol-secondary status
    PRIMARY NODE    PRIMARY VOL    PRIMARY BRICK    SECONDARY USER    SECONDARY                          SECONDARY NODE    STATUS    CRAWL STATUS       LAST_SYNCED
    mnode1          gvol-primary    /bricks/b1      geoaccount        snode1.example.com::gvol-secondary  snode1            Active    Changelog Crawl    2025-01-10 12:05:14

    STATUS should show Active once workers are running, and CRAWL STATUS reflects the current synchronization phase.