Any way to check the free space remaining in the datastore of the AR9331?


I am pretty sure a huge headache I was having was because I put too much data in the datastore of the AR9331. Is there any way to check how much free space is remaining in the datastore so I can avoid the problem in the future?

Can the 'df' command be of any help? e.g. 'df /mnt/sda' gives the information about the used/free/total space on the device.

kind regards,