Using Arch Linux / XFCE, I frequently have problems with USB drives that are not properly mounted. Sometimes they automatically show up in Thunar and I can mount them with one click. However, at other times (it's about fifty/fifty) the drive is just not recognized. I have had this problem with USB External Hard Drives, USB Memory Sticks, and cameras. If the external drive is not recognized, this is the situation:

• The drive does not show up at fdisk -l at all (it only shows my hard drives)
• The drive does not appear at /dev/disk
• The drive DOES appear when running lsusb

So there is some sort of recognition, but I do not understand why, nor do I know how to mount the drives when this happens. I just reboot and hope it works next time, which is clearly not convenient...