Time Machine can backup to a LaCie 6big or 12big RAID Storage drive when connected as Thunderbolt 3. However, these two RAID Storage drives will not be detected in MacOS Recovery Mode when connected as Thunderbolt 3. Therefore, a Time Machine Backup cannot be restored to an existing or replacement drive while in this configuration.
Connect the 6big or 12big RAID Storage Drive to the Mac using a USB C to C or USB C to A cable. Be sure to connect the cable to the USB C 3.1 port on the back of the 6big or 12big. The drive will now be detected in MacOS Recovery Mode and the Time Machine Backup can be restored to the existing or replacement disk drive.
Be aware that after connecting a 6big or 12big as USB, only the first RAID ARRAY and its volume will be detected in MacOS Recovery Mode, and the “Restore From Time Machine Backup" option.
It is common for a user to connect their 6 or 12big as Thunderbolt 3 and then create multiple RAID ARRAYs using the LaCie RAID Manager (LRM). If more than one ARRAY and volumes exist, be sure the Time Machine Backup is performed on the first ARRAY and volume that was created.