Dec 26, 2020
I have a few spare PC parts lying around. An AMD Ryzen 3 2200G (has its own graphic chips, no need for a dedicated GPU), some good and fast Corsair 8Gb RAM stick, an old Antec Sonata ATX case. Maybe a power supply but I don’t think so. I see a Kingston 250Gb SSD in a ThinkPad T400 (fr) I am not using at the moment.
Maybe I can buy the missing parts, and forge my own NAS to replace my aging Synology. It would be cheaper than buying a pricey Synology, right?
Not so fast. A PC is notoriously power inefficient while a "branded" NAS (Synology, QNAP, …) is low power. Let’s do some math. I assume the CPU is idle most of the time. The Ryzen 3 drains 25W. A 4-bay Synology DS418 uses 8.78W with "HDD Hibernation" "measured when it is fully loaded with Western Digital 1TB WD10EFRX hard drive(s)". The said WD Red HDD uses 0.4W in that state. So this would mean
8.78 - 4*0.4 or 7.90W for the NAS alone, excluding hard drives.
Let’s say the NAS lifespan is 8 years. This may seem long for a computer, but my ancient Synology is still running great after 12 years or so. It has witnessed several hard drive failures and it had to rebuild the RAID as many times. Of course the hardware may fail just outside the warranty period. In that case, granted, there is less room for self-repair on a branded NAS compared to a self-assembled PC.
Anyway, over the years, this difference in consumption amounts to 332.72€ for a device running 24/7 in favor of the Synology NAS.
The Total Cost of Ownership (TCO), for the appliance only, excluding the hard drives, can be estimated as follows:
Synology DS418: 399.00€ + 136.48€ electricity = 535.48€
DIY with spare parts: 168.83€ parts + 475.20€ electricity = 644.03€
We get a different picture in a scenario where the NAS is turned on 12h/day on week-ends and 4h/day during week days. In that case the TCO becomes favorable to the homemade PC NAS:
Synology DS418: 399.00€ + 52.80€ electricity = 451.80€
DIY with spare parts: 168.83€ parts + 186.86€ electricity = 352.69€
If you have no spare parts and have to buy everything, not only will the PC be slightly more expensive, but the electricity bill will make it a poor choice from an economic point of view, even in a scenario where it is not turned on 24/7.
Special IT freelancers in Belgium: many of us cannot deduce the cost nor reclaim VAT on electricity, so power consumption bears even more weight in our case.
There are considerations other than price:
Power consumption — Even if it was free or cheap, electricity production is most likely not good for the environment;
Noise — Unless you replace the CPU stock fan and opt for a silent PSU (further increasing the price), the PC DIY will produce more noise;
Heat — For sure the DIY PC will produce more heat;
Space — A branded NAS will be as compact as possible. Things are more complicated with a custom build. The MB and the PSU will inevitably increase the case size. My purpose was to reclaim an existing case, so I don’t have room (pun intended) for tweaking and would end up with a bulky mid-ATX tower;
Software — Run whatever you want on the PC, libre software or not, but it can require serious involvement. If you want a hassle-free solution, a branded NAS is appealing. If you want to build up some skills and enjoy fiddling, the DIY way is great. Personnaly, I like fiddling, but failures tend to happen unscheduled, preferably at the least convenient time. Ease of mind comes first;
Serviceability — A PC is much more amenable to modifications, upgrades and repairs. Specially the AMD Socket AM4 is a great choice;
Computing power — if you intend to do transcoding with Plex, the entry level branded NAS will not be sufficient. Most potent models exist but prices with soar;
Extra usage — Running custom scripts will be harder with a closed-source branded NAS.
Bear in mind all the figures I present are subject to interpretation. The "idle" hypothesis for instance may be inaccurate or even plain wrong. These numbers are rough estimates. Your cost for electricity may be different — copy the Google Sheet, adjust and find out.
At this stage, I am not building a custom NAS. I shall rely on my aging Synology, and will most likely buy a new one when its time comes — or find an alternative where I can avoid owning a NAS altogether.