diff --git a/duwatch/GNUmakefile b/duwatch/GNUmakefile
new file mode 100644
index 0000000..c1edc9f
--- /dev/null
+++ b/duwatch/GNUmakefile
@@ -0,0 +1,9 @@
+install: $(ROOT)/usr/local/bin/duwatch
+install_all:
+	make install ROOT=/nfs/wsrdb
+	make install ROOT=/nfs/wifosv
+	make install ROOT=/nfs/ihssv
+	make install ROOT=/nfs/wsrcom
+
+$(ROOT)/usr/local/bin/%: %
+	install $< $@
diff --git a/duwatch/duwatch b/duwatch/duwatch
new file mode 100755
index 0000000..d621cac
--- /dev/null
+++ b/duwatch/duwatch
@@ -0,0 +1,37 @@
+#!/usr/bin/perl
+
+$avgfile = "/usr/local/lib/duwatch.avg";
+$root = "/";
+$thresh = 20000;
+$period = 30;
+
+open AVG, $avgfile || die;
+while (<AVG>) {
+	($size, $name) = split;
+	$avgdu{$name} = $size;
+	$all{$name} = 1;
+}
+close AVG;
+
+open NEW, "/bin/du -t hfs $root |" || die;
+while (<NEW>) {
+	($size, $name) = split;
+	$size /= 2;	# du reports 512 byte blocks :-(
+	if ($size < $thresh) {next};
+	$newdu{$name} = $size;
+	$all{$name} = 1;
+}
+close NEW;
+
+for $i (keys %all) {
+	if ($newdu{"$i"} > 2 * ($avgdu{"$i"})) {
+		printf "%s: %d -> %d\n", $i, $avgdu{$i}, $newdu{$i};
+	}
+	$avgdu{$i} = ($avgdu{$i} * ($period - 1) + $newdu{$i}) / $period;
+}
+
+open AVG, ">" . $avgfile || die;
+for $i (keys %avgdu) {
+	printf AVG "%d %s\n", $avgdu{$i}, $i;
+}
+close AVG;