I've recently installed NanoNAS for a client and transferred all their data to the server. They have now decided that they want to use an external USB drive as a form of backup. Am I right that NanoNAS does not support USB and I will have to upgrade to NASlite-(M)2? Which version of NASlite-2 would I require and will the data be safe while I perform the upgrade as I would hate to lose all of their business documents? Is there any backup facility in NASlite or would I have to use some other software to perform the backup?