The product details here seem to indicate that it will support external drives:
Internal HDD: EXT4
External HDD: NTFS, EXT2, EXT3, FAT32, ReiserFS, XFS
Here is a review with some more clues...
- Other NAS backup strategies backup drives to externals as files when schduling "jobs". They are accessible from your computer using
the external drives if the NAS fails. This box does scheduled jobs in
a proprietary format, so you would have to by another Zyxel to
restore. There ARE two ways around some of this: A: A setting for the
front button will let you backup one of your shares and mirror it to
an external drive. You cannot schedule this though. B: You can use
drag-and-drop or software on your computer to cause files to
move/mirror to an external drive as files. BUT, since you are passing
through your CPU, it is slower and bound by that computer remaining
Honestly, it's not looking like you'll want to waste time with this...