Many SmallNetBuilder readers realize that the prices that companies like NETGEAR, QNAP, Synology, Thecus and others charge for their high-end "business class" NASes are significantly more than the cost of equivalent NASes that they could build themselves. Of course, we all realize that companies are in business to make a profit, so they aren't going to be giving the fruits of their labor away.
But sometimes, the difference between what you can build yourself and what you have to pay for what you can buy is big enough to make you take the plunge into building your own NAS.
Cloud backup company Backblaze had the same idea when they looked at the cost of buying "big iron" storage. Backblaze provides "cloud" based unlimited backup for $5 per month per Mac OS or Windows computer, including multiple versions. So they need a lot of storage, multiple petabytes (1 PB = 1,000 TB) worth, in fact.
They first looked at commercial solutions. But after pondering the comparison chart in Figure 1, they decided that they could recoup the cost of designing and building their own storage pretty quickly.
Figure 1: Cost of a Petabyte
I'm not going to go into all the details of Backblaze's design. They do a great job of that in their blog post that this article draws heavily from. Instead, I'll see what builders of much smaller DIY NASes can learn from Backblaze's exercise.
I'll note up front that Backblaze's design is not designed to reach 100 MB/s speeds; their web-based application simply doesn't demand it. But there are still valuable lessons to be learned.
The Basic Design
Backblaze's Storage Pod is made up of a custom metal case with commodity hardware inside. One pod contains one Intel Motherboard with four SATA cards plugged into it (Figure 2). The nine SATA cables run from the cards to nine port multiplier backplanes that each have five hard drives plugged directly into them (45 hard drives in total).
Figure 2: Exploded view
The two most important factors to note are that the cost of the hard drives dominates the price of the overall pod and that the rest of the system is made entirely of commodity parts.
The biggest hurdle that most NAS DIYers face is finding a suitable case. Having a custom case (Figure 2) designed and fabricated isn't feasible for most individuals. But creatively modding something that's close to what you want is.
For example, if you're willing to go with a three drive RAID system, I like the "Better Box" design using an Apevia Case and 3 bay SATA module.
If you're willing to spend a bit more for the benefit of no metal-bending, then Chenbro's ES34069 is a popular choice for four-drive designs.