Yes, I apparently did not read your original post correctly. Sorry about that. So chances are that the drive is filling up too quickly. I have also seen that issue with the tmp directory. Sadly, I do not have a fix for this. I had a time when my external mount was not mounted and moodle kept backing up to the temp folder and filled up the local hard drive and I about lost the site. Normally when the backups complete the tmp folder will be cleared out. I thought the trashdir was related to the recycle bin which has its own settings for deletion so it confuses me that that is continuing to grow. Have you checked your recycle bin settings - or maybe I am wrong in my assumption on that folder.