Upgrading NAS Hard Drives?

[Enquiries]

My WD EX2 Ultra 8TB is over 75% full using RAID 1. I've been thinking about buying WD PR4100 16TB (4x4TB) using RAID 5 and later upgrading the hard drives as necessary.

However a friend said I could'nt just replace one 4TB with one 8TB and expect RAID to recover the replaced 4TB onto the new 8TB and then also have additional space. I had to replace all 4TB drives with all 8TB at the same time and somehow use another device to transfer the data from the old 4TB drives to the new 8TB drives.

Is that correct? If so what is the process others use to upgrade their hard drives?

Can you please clarify how I can buy something I can afford now and upgrade later as the need arises and funds become available?

Thanks, Xaviour

[ed]

You should be able to replace it with a bigger drive. But it is true. You would need to replace one drive at a time and let it rebuild. When both drives are replaced, capacity should increase.But Qnap and Synology are simpler to upgrade compared to WD. They actually have a function to do this. Also with a Synology, you can mix different size drives and get a bigger capacity without replacing all drives.DS920+ and TS-453D would be alternatives to this PR series WD NAS.I hope this helps.