## Replica Modification sync

replication is configured, any incoming uploads and metadata changes to versions created on the target, will sync back to the source and be marked as `REPLICA` on the source. AWS, as well as MinIO do not by default sync metadata changes on a object version marked `REPLICA` back to source. This requires a setting in the replication configuration called [replica modification sync](https://aws.amazon.com/about-aws/whats-new/2020/12/amazon-s3-replication-adds-support-two-way-replication/).

For active-active...

	for k, v := range o.ErrCounts {
		n.ErrCounts[k] += v
	}
	return n
}

// SRStats has replication stats at site level
type SRStats struct {
	// Total Replica size in bytes
	ReplicaSize int64 `json:"replicaSize"`
	// Total Replica received
	ReplicaCount int64                `json:"replicaCount"`
	M            map[string]*SRStatus `json:"srStatusMap"`

	ReplicatedSize int64 `json:"completedReplicationSize"`
	// Total Replica size in bytes
	ReplicaSize int64 `json:"replicaSize"`
	// Total failed operations including metadata updates for various time frames
	Failed madmin.TimedErrStats `json:"failed"`

	// Total number of completed operations
	ReplicatedCount int64 `json:"replicationCount"`
	// Total number of replica received
	ReplicaCount int64 `json:"replicaCount"`

		case replication.Pending, replication.Completed, replication.Failed, replication.Replica: // for backward compatibility
			return replication.StatusType(rs.ReplicationStatusInternal)
		default:
			replStatus := getCompositeReplicationStatus(rs.Targets)
			// return REPLICA status if replica received timestamp is later than replication timestamp
			// provided object replication completed for all targets.

# Automatic Site Replication

This feature allows multiple independent MinIO sites (or clusters) that are using the same external IDentity Provider (IDP) to be configured as replicas. In this situation the set of replica sites are referred to as peer sites or just sites. When site-replication is enabled on a set of sites, the following changes are replicated to all other sites:

- Creation and deletion of buckets and objects

		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrReplicationPermissionCheckError), r.URL)
		return
	}

	replica := r.Header.Get(xhttp.AmzBucketReplicationStatus) == replication.Replica.String()
	if replica {
		if s3Error := checkRequestAuthType(ctx, r, policy.ReplicateDeleteAction, bucket, object); s3Error != ErrNone {
			writeErrorResponse(ctx, w, errorCodes.ToAPIErr(s3Error), r.URL)

	ReplicationTimestamp = "replication-timestamp"
	// ReplicaStatus - this header is present if a replica was received by this cluster for this object version
	ReplicaStatus = "replica-status"
	// ReplicaTimestamp - the last time a replica was received by this cluster for this object version
	ReplicaTimestamp = "replica-timestamp"
	// TaggingTimestamp - the last time a tag metadata modification happened on this cluster for this object version

			return
		}

		metadata[xhttp.AmzObjectTagging] = objTags
	}
	if r.Header.Get(xhttp.AmzBucketReplicationStatus) == replication.Replica.String() {
		metadata[ReservedMetadataPrefixLower+ReplicaStatus] = replication.Replica.String()
		metadata[ReservedMetadataPrefixLower+ReplicaTimestamp] = UTCNow().Format(time.RFC3339Nano)
	}

	Cached     bool // true only when we are requesting a cached response instead of hitting the disk for example ListBuckets() call.
	NoMetadata bool
}

// SetReplicaStatus sets replica status and timestamp for delete operations in ObjectOptions
func (o *ObjectOptions) SetReplicaStatus(st replication.StatusType) {
	o.DeleteReplication.ReplicaStatus = st
	o.DeleteReplication.ReplicaTimeStamp = UTCNow()
}