Multi-site considerations
A Ceph Object Gateway multi-site configuration requires at least two IBM Storage Ceph clusters, and at least two Ceph Object Gateway instances, one for each IBM Storage Ceph cluster. Typically, the two IBM Storage Ceph clusters are in geographically separate locations; however, this same multi-site configuration can work on two IBM Storage Ceph clusters at the same physical site.
Multi-site configurations require a primary zone group and a primary zone. Additionally, each zone group requires a primary zone. Zone groups might have one or more secondary zones.
Configure multi-site either through the CLI or through the dashboard. See Configuring a
multi-site for more details.
Important: The primary zone within the primary zone
group of a realm is responsible for storing the primary copy of the realm’s metadata, including
users, quotas, and buckets. This metadata gets synchronized to secondary zones and secondary zone
groups automatically. Metadata operations issued with the radosgw-admin command
line interface (CLI) MUST be issued on a node within the primary zone of the primary zone
group to ensure that they synchronize to the secondary zone groups and zones. Currently, it is
possible to issue metadata operations on secondary zones and zone groups, but it is NOT
recommended because they WILL NOT be synchronized, which can lead to fragmentation of the
metadata.
The following diagrams illustrate the possible one and two realm configurations in
multi-site Ceph Object Gateway environments.
