diff --git a/weed/filer/filer.go b/weed/filer/filer.go
index 4595c55f4..bd349af67 100644
--- a/weed/filer/filer.go
+++ b/weed/filer/filer.go
@@ -56,6 +56,7 @@ type Filer struct {
 	MetaAggregator          *MetaAggregator
 	Signature               int32
 	FilerConf               *FilerConf
+	placementOverlay        PlacementOverlay
 	RemoteStorage           *FilerRemoteStorage
 	lazyFetchGroup          singleflight.Group
 	lazyListGroup           singleflight.Group
@@ -96,6 +97,10 @@ func NewFiler(masters pb.ServerDiscovery, grpcDialOption grpc.DialOption, filerH
 	f.metaLogCollection = collection
 	f.metaLogReplication = replication
 
+	if newPlacementOverlay != nil {
+		f.placementOverlay = newPlacementOverlay(f)
+	}
+
 	go f.loopProcessingDeletion()
 
 	return f
diff --git a/weed/filer/placement_overlay.go b/weed/filer/placement_overlay.go
new file mode 100644
index 000000000..9c9f80873
--- /dev/null
+++ b/weed/filer/placement_overlay.go
@@ -0,0 +1,36 @@
+package filer
+
+// PlacementOverlay resolves a write-time placement override for a collection —
+// the disk type, replication, and data center new volumes of that collection
+// should land on — or ok=false when the collection has none.
+//
+// It exists so a feature can steer where a bound collection's data lands without
+// every operator setting an fs.configure rule by hand. The type is deliberately
+// generic: it names no placement-policy concepts, so a downstream build
+// registers whatever overlay it wants without coupling this seam to it.
+type PlacementOverlay func(collection string) (diskType, replication, dataCenter string, ok bool)
+
+// newPlacementOverlay builds the overlay for a filer. Enterprise sets it in an
+// init() pulled in by a side-effect import, the way plugin-worker handlers
+// register — the setter cannot live here because this package is overwritten by
+// the sync.
+var newPlacementOverlay func(*Filer) PlacementOverlay
+
+// RegisterPlacementOverlay installs the factory. It is meant to be called from a
+// package init() — before any Filer is constructed and before serving starts —
+// so the unsynchronized read in NewFiler never races the write. The last
+// registration wins; there is only ever one overlay.
+func RegisterPlacementOverlay(factory func(*Filer) PlacementOverlay) {
+	newPlacementOverlay = factory
+}
+
+// ResolvePlacement returns the overlay's placement for a collection, or
+// ok=false when there is no overlay or the collection is not steered. The write
+// path applies these between the explicit request value and the filer.conf
+// rule, so an overlay overrides the rule but yields to an explicit request.
+func (f *Filer) ResolvePlacement(collection string) (diskType, replication, dataCenter string, ok bool) {
+	if f == nil || f.placementOverlay == nil || collection == "" {
+		return "", "", "", false
+	}
+	return f.placementOverlay(collection)
+}
diff --git a/weed/server/filer_server_handlers_write.go b/weed/server/filer_server_handlers_write.go
index f44f53004..1344c67f5 100644
--- a/weed/server/filer_server_handlers_write.go
+++ b/weed/server/filer_server_handlers_write.go
@@ -295,14 +295,29 @@ func (fs *FilerServer) detectStorageOption(ctx context.Context, requestURI, qCol
 		ttlSeconds = int32(ttl.Minutes()) * 60
 	}
 
+	collection := util.Nvl(qCollection, rule.Collection, bucketDefaultCollection, fs.option.Collection)
+
+	// A placement overlay steers a bound collection's new volumes onto a tier.
+	// It sits between the explicit request and the filer.conf rule: it overrides
+	// the rule but yields to a value the caller asked for outright. Only a
+	// steered collection contributes values; an unsteered one clears them so it
+	// falls straight through to the rule.
+	overlayDisk, overlayReplication, overlayDataCenter, overlaySteered := fs.filer.ResolvePlacement(collection)
+	if !overlaySteered {
+		overlayDisk, overlayReplication, overlayDataCenter = "", "", ""
+	} else {
+		glog.V(4).InfofCtx(ctx, "placement overlay steers collection %s: disk=%q replication=%q dataCenter=%q",
+			collection, overlayDisk, overlayReplication, overlayDataCenter)
+	}
+
 	return &operation.StorageOption{
-		Replication:       util.Nvl(qReplication, rule.Replication, fs.option.DefaultReplication),
-		Collection:        util.Nvl(qCollection, rule.Collection, bucketDefaultCollection, fs.option.Collection),
-		DataCenter:        util.Nvl(dataCenter, rule.DataCenter, fs.option.DataCenter),
+		Replication:       util.Nvl(qReplication, overlayReplication, rule.Replication, fs.option.DefaultReplication),
+		Collection:        collection,
+		DataCenter:        util.Nvl(dataCenter, overlayDataCenter, rule.DataCenter, fs.option.DataCenter),
 		Rack:              util.Nvl(rack, rule.Rack, fs.option.Rack),
 		DataNode:          util.Nvl(dataNode, rule.DataNode, fs.option.DataNode),
 		TtlSeconds:        ttlSeconds,
-		DiskType:          util.Nvl(diskType, rule.DiskType),
+		DiskType:          util.Nvl(diskType, overlayDisk, rule.DiskType),
 		Fsync:             rule.Fsync,
 		VolumeGrowthCount: rule.VolumeGrowthCount,
 		MaxFileNameLength: maxFileNameLength,