From the Knowledge Base: https://support.presonus.com/hc/en-us/articles/115001081306-PreSonus-StudioLive-Series-III-Using-Onboard-SD-Card-Recording "Due to the nature of flash memory though, depending on the size of the sessions deleted, the size of the card, and the amount of used space, this will only work for a short while before the performance of the card degrades, so ideally, you should do a full format of the card using the SDCard.org format utility."