yes but please don't consider the raid1 a self backed up drive. Raid 1 will survive a single drive failure but will not protect you from user error (opps I deleted the partition), viruses, file corruption, system-wide hardware failure like a nearby lightning strike that kills all 4 drives and the NAS..., environmental disasters (fire, flood, malicious pets...), theft....
Only an unpowered off-site backup would survive some of these events.