Unsuitable for backup! I have the DS-412 + for about 2 years in operation equipped with 4x WD30EURS 3TB Server disks in Raid 5 mode. At the weekend failure of the plate in the Bay 2. No problem, I thought, but one has to Raid5. Old plate out, purely new and everything should go back. Forget it! System crash, no longer have access via the Disk Manager. 1day rumprobiert, finally with Linux PC tries a RAID to the plates build. Result: No way. Have all 4 plates returned to Datt rescue company. Result still open. Conclusion: great multimedia capabilities, all four streaming on Apple TV. But there's 4 stars. Data security is a disaster, it's is 1 star. Power 2 stars. I can only advise either to operate 2 Synologies parallel, or in addition externally to create backups in the cloud or on external HDs.