Backup USB-SSD > NAS HDD

Synology won’t use a USB-SSD as source for backup, so you need a mount

Create a shared folder on Synology NAS,

• Via File Station on Synology DSM
• Create Shared Folder, e.g usb_source

sudo mount --bind /volumeUSB1/usbshare /volume1/usb_sourceCopy

Now you can use the usb_source shared folder (which is mounted to the USB-SSD) as backup source