↳ In-reply-to » (#sdorpga) @mckinley I am curious now, though. Doesn't Synology use RAID Btrfs? How in the world do they do it? Researching...

Ha! Found it:

Due to the Btrfs RAID issues, Synology chose Linux RAID. Based on the diagram below, Synology has implemented the layers in between the file systems and disks to ensure that Synology has full control to achieve the highest stability.