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
	}

	w.Header().Set(tierCfgRefreshAtHdr, globalTierConfigMgr.refreshedAt().String())