tiered storage: can copy to s3, read from s3

master not aware tiered volume yet, file assigning is not working yet

weed/storage/volume_loading.go

@@ -26,8 +26,11 @@ func (v *Volume) load(alsoLoadIndex bool, createDatIfMissing bool, needleMapKind
 	fileName := v.FileName()
 	alreadyHasSuperBlock := false
 
-	// open dat file
-	if exists, canRead, canWrite, modifiedTime, fileSize := checkFile(fileName + ".dat"); exists {
+	if v.maybeLoadVolumeTierInfo() {
+		// open remote file
+		alreadyHasSuperBlock = true
+	} else if exists, canRead, canWrite, modifiedTime, fileSize := checkFile(fileName + ".dat"); exists {
+		// open dat file
 		if !canRead {
 			return fmt.Errorf("cannot read Volume Data file %s.dat", fileName)
 		}