starting point with nas

[nas_max]

Hi,
if I start with 2 disk´s in raid 1 and I will expand later can I set another 2 disk raid 1 and bundle it to raid 10 subsequently without data loss?
( ... is this possible in QuTS hero ZFS or in DSM with BTRFS ... ? )

That is the crucial question for my decision for my first nas. 

Thanks and regards,
max.

[ed]

If you start with two drives, you have few options. You can add another drive or two and set a separate RAID. Or you can merge all drives together and migrate to RAID5.
RAID1 to RAID10 doe not work.