diff --git a/etcdserver/metrics.go b/etcdserver/metrics.go
index 88ff158b7..7d57b8115 100644
--- a/etcdserver/metrics.go
+++ b/etcdserver/metrics.go
@@ -41,6 +41,12 @@ var (
 		Name:      "leader_changes_seen_total",
 		Help:      "The number of leader changes seen.",
 	})
+	heartbeatFailures = prometheus.NewCounter(prometheus.CounterOpts{
+		Namespace: "etcd",
+		Subsystem: "server",
+		Name:      "heartbeat_failures_total",
+		Help:      "The total number of heartbeat send failures (likely overloaded from slow disk).",
+	})
 	proposalsCommitted = prometheus.NewGauge(prometheus.GaugeOpts{
 		Namespace: "etcd",
 		Subsystem: "server",
@@ -90,6 +96,7 @@ func init() {
 	prometheus.MustRegister(hasLeader)
 	prometheus.MustRegister(isLeader)
 	prometheus.MustRegister(leaderChanges)
+	prometheus.MustRegister(heartbeatFailures)
 	prometheus.MustRegister(proposalsCommitted)
 	prometheus.MustRegister(proposalsApplied)
 	prometheus.MustRegister(proposalsPending)
diff --git a/etcdserver/raft.go b/etcdserver/raft.go
index 45733512f..e69dfc504 100644
--- a/etcdserver/raft.go
+++ b/etcdserver/raft.go
@@ -293,6 +293,7 @@ func (r *raftNode) sendMessages(ms []raftpb.Message) {
 				// TODO: limit request rate.
 				plog.Warningf("failed to send out heartbeat on time (exceeded the %v timeout for %v)", r.heartbeat, exceed)
 				plog.Warningf("server is likely overloaded")
+				heartbeatFailures.Inc()
 			}
 		}
 	}