Hard Drive/ Size to Purchase

[Enquiries]

I recently purchased a Synology NAS 920+ on blackfriday. I currently have about 5tb of movie files in different file types. on a computer I was using Plex I want to move my data to a NAS. After following your youtube videos I noticed if using 2 hard drives in raid 1 I'll lose half of the space for redundancy. It appears I should be purchasing a larger drive for growth is this agreeable based on the information I've supplied? If I'm understanding correctly I probably should buy 2 16tb or 18tb drives for growth? I will probably only buy one drive to start I didn't realize it. would be so costly

[ed]

Yes, RAID or SHR with two drives will create a mirror. Having 3 drives or more will sacrifice 1 drive for redundancy (33% capacity).
You could add a third drive and migrate to RAID5/SHR1. SHR allows different-size drive mixing.

I hope this helps.