If you're thinking about building a NAS here is a build for you. It will focus on the following aspects.
- Power efficiency - its supposed to run 24/7 after all and you don't want to notice it on your power bill.
- Enough compute power - This machine should be able to comfortably handle storage-parity calculations (Raid5/RaidZ) and saturate the gigabit NIC.
- ECC support - so you can run ZFS which is also the default for FreeNAS.
A system without the actual HDD storage drives should set you back less than £300. A system with 6 HDDs should cost you around £36-£70 in power per year assuming you pay 12 pence per kilowatt-hour.
This post is going to be continuously updated as components change, so come back if you decide to upgrade or build another in 6 months etc.
If AMD releases a low power Ryzen 3 part, I will likely replace this build or append it as another alternative build, but this will also depend upon motherboard ECC support/pricing.
We needed a cheap, low power part that will support ECC memory. If you don't think it supports ECC because its not a Xeon, check the ark intel page.
The important factor is that both of these boards use the C232 chipset for the ECC support. However, the downside is that the boards don't have any video output ports, so you will likely need to plug in a spare graphics card for the setup at least. The gaming one is slightly more expensive but has some features like 7.1 surround sound which shouldn't really matter for a NAS.
This depends a lot on your setup, but make sure to get DDR4 unbuffered ECC memory that you can get (which is really expensive right now and prices are likely to fluctuate often). Make sure to pick a capacity you are comfortable with as you only have 4 DIMM slots and may need to expand. The rule of thumb is that you need 1 GB per TB of storage in your NAS (if you are using ZFS/FreeNAS), but I think you could give up on this rule once you get to 32GB of RAM and should look into an L2ARC storage drive if you get to this level.
If you are not using ZFS/FreeNAS then you probably don't need much RAM and could get by with a single 4GB stick. Non ZFS NAS systems include unRAID, which uses BTRFS, which I do not recommend after the stability issues I had with BTRFS on Ubuntu. You could also be using traditional hardware RAID, or mdadm which don't require lots of memory.
This case is relatively cheap whilst supporting 6 x 3.5 inch drives.
I would go with a cheap brand name PSU with as low wattage as you can get. You can spend more on getting a "platinum" rated one if you want, but I 80plus is good enough for me. We deliberately targeted a low wattage CPU, and hard drives really don't take much power. Also, you should not be using a graphics card in this computer so you don't have to worry about that. Your PSU should be providing around 50-80% of its rated power, so getting a massive 600 watt PSU is stupid if you are only being used to provide 40 watts of power total. Unfortunately, low-power PSUs are often more expensive than their higher wattage counterparts.
I only use WD Reds for my storage drives. I have been using 8 of the 3TB drives, and 2 of the 4 TB drives and have yet to have a failure. The red line is targeted specifically at NAS systems, for running 24/7 and will spin at a lower 5400 RPM for endurance, rather than the traditional 7200 RPM. Please do not buy the slightly cheaper "green" drives and I've heard too many horror stories about Seagate drives which do not come off well in the yearly Backblaze reports (2017) on storage drives.
Often these NAS systems can boot off of a USB (£7) which means one more free SATA port and can be a cheap solution, especially if you have one lying around. I linked a SanDisk ultra because I found that it had good performance and you really don't need much capacity. Alternatively, you can use a 2.5 inch SSD or spining disk if you are concerned about using a flash drive for your OS, and use a USB3 adapter to connect so as to not take up one of your precious SATA ports.
Unfortunately, the processor listed here is a Kaby Lake part and will require a later version of the BIOS in order to work as shown here. Please make sure that either the vendor of the motherboard is willing to sell you the BIOS after having upgraded it, or that you have a spare Skylake CPU available to update the BIOS with before using the Pentium. Alternatively, you can do what I have done and buy a chip to stick in the motherboard to update it.