diff --git a/configuration/on-site-scripts/monitor-mongo-disk-full b/configuration/on-site-scripts/monitor-mongo-disk-full
new file mode 100644
index 00000000000..936795b5fa5
--- /dev/null
+++ b/configuration/on-site-scripts/monitor-mongo-disk-full
@@ -0,0 +1,6 @@
+#!/bin/bash
+WARN_THRESHOLD_PERCENT=80
+mongo_volume_fill=$( ssh ec2-user@tokyo-ssh.sapsailing.com df /var/lib/mongo | awk '{ print $5; }' | tail -n 1 | sed -e 's/%$//' )
+if [ ${mongo_volume_fill} -gt ${WARN_THRESHOLD_PERCENT} ]; then
+  notify-operators "MongoDB volume on tokyo-ssh.sapsailing.com almost full; currently at ${mongo_volume_fill}%"
+fi