-growisofs -dvd-compat -Z ${device_name}=${iso_name}
-#used to be appended to above line: -speed=2
-#trying with letting it go default speed. has been working for us recently.
+growisofs -dvd-compat -speed=2 -Z ${device_name}=${iso_name}
+#hmmm:
+# 1) trying with letting it go default speed. has been working for us recently.
+# 2) lots of failures on bluray burns recently; trying dropping the speed back to 2.
+# 2024-01-14
+