Is adding drives in stages possible?

[Enquiries]

Years ago I had a small (2 bay) netgear readynas duo desktop nas that had a proprietary (?) Raid on it that would allow me to add drives on the fly and it would resize the array to expand.

For instance if I had 2 250 Gig hard drives, I could later just swap in a single 500 Gig hard drive a few months later. It would all resize. In theory. It worked until it finally died.

I'm about to finally buy a QNAP TS-873AeU-4G-US. Can I put in four drives now and add more later? I really can't find this kind of information? Or do I need to wait longer till I save up the money to buy all 8 drives to start?

[ed]

Yes, Qnap will allow you to start with just few drives. You can add drives later and expand storage space. But adding bigger drives than existing ones will limit expansion based on the original drive size.
If you go for Synology such as ds1821+, you can mix different size drives, as you described.

I hope this helps.