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?
3.5" are cheaper, go up to higher capacities (2.5" maxes out at only 5TB IIRC), and are easier to find cheap in used/refurb formats.
I wouldn’t use 2.5" unless you absolutely had to for some reason.
The 2.5" drives are significantly more power efficient, often by a factor of 10. They also tend to be less noisy and produce less heat.
So in a small form factor NAS that isn’t under heavy load, 2.5” drives are usually the better option.
It looks like about 2-3W with 2.5" vs 6-8W with 3.5"
So 3.5" drives are going to be more efficient, since you can get one that’s 4x the capacity (20TB vs 5TB) for only a little over double the power usage.
Less noise is definitely a bonus if your NAS sits next to your workstation or something though.
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.
