They take me to the former factory building on the outskirts of Tallinn. Fortunately, I am not in the trunk, but they asked me to keep the destination a secret and not to take any photos of the exterior, so that the exact location remains hidden from the ill-intentioned individuals. It is surprising, but for some reason there are a lot of those who wish to find it. 


It’s unlikely that there is a single person in the world who woke up one day with the thought “What if I build a personal data center today?”. Usually people come to such decisions through a chain of events and conditions. 



HashFlare made this decision as a result of a combination of factors, the very first and important one being the excitement for the new cryptocurrency. Ethereum boomed and reached capitalization of almost a billion US dollars within a little over a year. Of course, HashFlare customers also wanted to get an opportunity to mine this new cryptocurrency.



Ethereum is best mined on video cards. A lot has been written to explain the advantages of mining on video cards over mining on CPU. Unique features of some cryptocurrencies, Ethereum included, make CPU mining very impractical. For example, if the currency uses several encryption algorithms in a certain sequence, any change of the algorithm will result in a system failure. Ethereum uses a very complex algorithm, which makes it completely impossible to be mined on CPU, while GPU mining is possible for almost any currency. 



However, it is not as simple as just putting a bunch of video cards into racks in a data center. The main complication here is cooling. Cases of modern servers are designed for the most effective cooling: with the air intake on one side and the air outlet on the other. Even ASIC miners have long since been available in standard cases mountable in server racks of data centers. Video card producers don’t bother with such functionality, as they could not foresee that an idea of developing whole GPU farms could ever be possible. It is impossible to mount video cards in an enclosed rack, as all of them are facing different directions, while, at the same, time if something goes wrong (failure of fans or other problems may arise), you have to be able to disconnect and remove the broken link. 


In such moments, you begin to appreciate the maintainability


Of course, video cards could be mounted in computer cases but it will increase the overall price greatly and affect their serviceability. This is a small-scale solution for only 1 or 2 video cards, which makes it ineffective for industrial use. 

Besides, administrators of data centers are not trained to work with video cards and have no desire to do it. 

So, we need a mining farm on video cards which is impossible to deploy in an ordinary data center. You already know the solution – build it yourself. And now we will talk about the ways to do it.



In early March, HashFlare announced the launch of Ethereum mining and started accepting pre-orders, which provided sufficient funds to build the first GPU mining farm for Ethereum, launched later in early April 2016.



For this farm the company rented out several large storage rooms within the building of a former Soviet factory on the outskirts of the Estonian capital. The temperature in the spacious and cool building rises dramatically as you approach the premise, where the magic of mining happens. It is so hot inside that the admins wearing sleeveless sports shirts and shorts do not look adequately dressed. Here you want to take off not only your clothing but also your skin. 



Cooling turns out to be the cornerstone of your own data center: HashFlare have reconstructed the entire ventilation system of the premises according to its needs. 


Standard air duct has no chance to meet the requirements of a mining farm



If you ever decide to sell your soul to the devil in exchange for a work-space in a tropical environment, don’t forget to note that it has to be Thailand and not a mining farm. Otherwise, you can find yourself wearing shorts and flip-flops in the middle of Estonia: 


At work like on the beach


Engineers calculated that to keep the temperature of hardware consuming 100 kWh, according to ambient temperature of +25°С, at least at +35°C, the air exchange has to be 35,000 m³/h. It means that you need at least a 5 m² hole for fresh air intake, and 2 air ducts of 630 mm each with fans for air outlet.

While ventilation is under reconstruction, any help is appreciated


Apart from the overwhelmingly complex cooling systems, the rest seems as easy as piecing together Lego’s: Asrock H81 Pro BTC mother boards, AMD R9 380, R9 380x (Sapphire/MSI) video cards, PCI-E risers used to connect a number of video cards to a limited number of GPU slots on a standard motherboard, and EVGA SuperNOVA 1300 G2 1300W power units are mounted in standard metal racks. 


Demand for Ethereum mining is growing constantly, hence only in Tallinn HashFlare is going to occupy another similar premise close to the first building. At the moment there are only empty shelves with dozens of connected sockets there, but soon everything will change. 


One more data center for 50 GH/s will be opened soon near the premises of an Estonian hydroelectric power plant. The name of this HPP is also kept a secret, but a data center located in a hydroelectric power plant – it sounds really cool!


Maybe, this HPP looks something like this. But more likely it’s not, as this photo was not taken in Estonia.


Security


When you build your own data center, the next priority after equipment and cooling is security. Information makes money, and in this case information is money, even if it’s virtual money. 

Obviously, video cameras are installed in all corners of the farm: 

And you can see what is happening there online using your phone any time: 

At the moment more than a thousand video cards are working for HF’s clients mining more than 20 Ghs per second to find valuable coins. The scale is constantly growing: the total performance of all HashFlare farms should exceed 100 Ghs/sec. You can start cloud mining Ethereum right now: ether.hashflare.eu 



Of course, capabilities of the farm are not limited to Ethereum. This is another advantage of mining on GPU’s – you can mine any currency regardless of the difficulty of its mining algorithm, that is why HashFlare uses a portion of the Hashrate of its farm to experiment with new promising or simply interesting currencies like Dashcoin and some others.