Starting with ICS, Android phones were no longer required to have a physical SD card. This is why on devices such as the Nexus “/sdcard” is just emulated and points to the “/data” partition where all of your apps reside.
So how do you monitor the external SD card if ZW will not distinguish between internal and external storage? Well, just manually add the path:
#SF/mnt/extSdCard/# -> Will show sdcard free space
#ST/mnt/extSdCard/# -> Will show sdcard total space
#SF/mnt/extSdCard/M# -> Will show sdcard free space in megabytes
#ST/mnt/extSdCard/M# -> Will show sdcard total space in megabytes
The paths may differ slightly on your device, so check your SD card path first. This trick isn't just for external SD cards. It will also allow you to monitor your /cache or /system filesystems if you want, too.