Hi eskimo, Thanks for your kindly sharing. I read the document but still be confused. Although I use old api to print available space, but I did get the disk full error when I saving a video to disk which size 26GB is much less than 180GB shows in iOS Settings. I would like to ask why this situation happens and what error handling should I do? According to the information you mentioned before, is it means that sytem cache about 150 GB information so I can not write 26GB video to disk? If it does, how should I do to handle this error to make my write action could be succeed? Will it help if I wait several seconds and try writing again? Or can I do any action to force system purge cache ASAP? Thanks~