ctx := r.Context()

	objAPI, _ := validateAdminReq(ctx, w, r, policy.ListTierAction)
	if objAPI == nil {
		return
	}

	tiers := globalTierConfigMgr.ListTiers()
	data, err := json.Marshal(tiers)
	if err != nil {
		writeErrorResponseJSON(ctx, w, toAdminAPIErr(ctx, err), r.URL)
		return
	}

	RenameData(ctx context.Context, srcVolume, srcPath string, fi FileInfo, dstVolume, dstPath string, opts RenameOptions) (RenameDataResp, error)

	// File operations.
	ListDir(ctx context.Context, origvolume, volume, dirPath string, count int) ([]string, error)
	ReadFile(ctx context.Context, volume string, path string, offset int64, buf []byte, verifier *BitrotVerifier) (n int64, err error)