Been finding some good deals on 2.5 disks lately, but have never bought one before. Have a couple of 3.5 disks on the other hand in my Unraid server. Wondering how much it matters wether I get a 2.5 or not? What form factor do you prefer/usually go for?
It is true that if you need a lot of space at some point 3.5" are going to be more efficient per GB, but usually people don’t need hundreds of terabyte storage in a home NAS.
For normal applications in a home NAS that mostly sits idle, 2.5" drives run at about 1W and most are design to be able to be powered by normal USB, meaning 2.5W max.
3.5" drives on the other hand are usually designed for datacenter use, where power efficiency is a low priority and they usually take 5-10W in normal operation and and easily 15W when spinning up.
I don’t even have all that much storage (18TB usable), the other side of things is I’d need 8x 5TB 2.5" drives in RAID 10 to be equal my 2x 18TB 3.5" drive mirror I have now, which means I’d need to add an HBA card that also consumes more power. Even if I ran RAIDz2 I’d still need 6 drives.
Price is another factor, from some poking around 2.5" is around 2x the cost of what I paid for my 3.5" drives.