Using multi-site sync policies

As a storage administrator, you can use multi-site sync policies at the bucket level to control data movement between buckets in different zones. These policies are called bucket-granularity sync policies. Previously, all buckets within zones were treated symmetrically. This means that each zone contained a mirror copy of a given bucket, and the copies of buckets were identical in all of the zones. The sync process assumed that the bucket sync source and the bucket sync destination referred to the same bucket.

Important: Bucket sync policies apply to data only, and metadata is synced across all the zones in the multi-site irrespective of the presence of the bucket sync policies. Objects that were created, modified, or deleted when the bucket sync policy was in allowed or forbidden place, it does not automatically sync when policy takes effect. Run the bucket sync run command to sync these objects.
Important: If there are multiple sync policies defined at zonegroup level, only one policy can be in enabled state at any time. We can toggle between policies if needed

The sync policy supersedes the old zone group coarse configuration (sync_from*). The sync policy can be configured at the zone group level. If it is configured, it replaces the old-style configuration at the zone group level, but it can also be configured at the bucket level.

When the sync policy of a bucket or zonegroup moves from disabled to enabled state, the following behavioral changes are observed:

  • Greenfield deployment - To set up bucket granular sync replication, a new zonegroup, or zone must be configured at a minimum.

  • Brownfield deployment - Migrate or upgrade Ceph Object Gateway multi-site replication configurations to the newly featured bucket granular sync policy replication.

  • Data flow - directional, symmetrical - Both unidirectional and bi-directional (symmetrical) replication can be configured.

Note: The bucket sync policies are applicable to the archive zones. The movement from an archive zone is not bidirectional wherein all the objects can be moved from active zone to archive zone. However, you cannot move objects from the archive zone to active zone since archive zone is read-only.
Important: In this release, the following features are not supported:

  • Source filters

  • Storage class

  • Destination owner translation

  • User mode

Prerequisites

  • A running IBM Storage Ceph cluster.
  • Root-level access to a Ceph Monitor node.
  • Installation of the Ceph Object Gateway.